Evaluation of the release of nickel and titanium under orthodontic treatment.

The metal alloys used in dentistry are made mainly of nickel (Ni), titanium (Ti), and other elements such as molybdenum (Mo), zirconium (Zr), iron (Fe), tin (Sn), chrome (Cr), carbon (C), copper (Cu) and niobium (Nb) which can release metal ions in unstable environments. The aim of this work was determine the salivary pH before and during orthodontic treatment; evaluate the release of metal ions, mainly Ni and Ti, in urine and saliva using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES); and evaluate the corrosion using Scanning Electronic Microscopy (SEM). In this study, we selected 35 individuals under orthodontic treatment, from whom saliva and urine samples were collected in 3 stages: (a) basal, (b) at 3 and (c) 6 months after the placement of the fixed appliances. SEM analyzed the Ni-Ti (0.016″) and stainless steel (SS) (0.016 × 0.022″) archs after 1 month of being in contact with the oral cavity. Statistical analysis was performed with Stata using the ANOVA model of repeated measures with a p < 0.05. A statistically significant difference in the concentration of Ni in saliva were found between 3 and 6 months of intervention and Ti in urine was found 3 and 6 months.

Side Effects of Dental Metal Implants: Impact on Human Health (Metal as a Risk Factor of Implantologic Treatment).

Dental implants are often made of titanium alloys. Implant therapy currently promises a good long-term result without impacting health; however, its success depends on many factors. In this article, the authors focus on the most common risk factors associated with metallic surgical implants. Titanium-induced hypersensitivity can lead to symptoms of implant rejection. Corrosion and biofilm formation are additional situations in which these symptoms may occur. For medical purposes, it is important to define and discuss the characteristics of metals used in implantable devices and to ensure their biocompatibility. To avoid hypersensitivity reactions to metallic dental implants, precautionary principles for primary prevention should be established.

Metal-free materials for fixed prosthodontic restorations.

BACKGROUND: Fixed prosthodontic treatment (crowns, fixed dental prostheses (FDPs), complete arch prostheses) involves the use of several different materials to replace missing tooth structure. Traditionally full metal or metal frameworks veneered with ceramic (metal-ceramic (MC)) have been used. In recent years several different metal-free systems have become available to clinicians and patients. In general, metal-free restorations should allow practitioners to better reproduce natural tooth colour, avoiding shortcomings of MC restorations. The comparative in service clinical performance of fixed prosthodontic treatments of different materials is unclear. OBJECTIVES: To assess the effects of metal-free materials for prosthodontic restorations compared to metal-ceramic or other conventional all-metal materials. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (searched 3 May 2017), Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 4) in the Cochrane Library (searched 3 May 2017), MEDLINE Ovid (1946 to 3 May 2017), and Embase Ovid (1980 to 3 May 2017). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials (searched 3 May 2017). No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: Randomised controlled trials (RCTs) in which the clinical performance of metal-free fixed prosthodontic restorations was compared with metal-ceramic (MC) or other conventional restorations in adult patients requiring prosthodontic treatment. RCTs in which the clinical performance of different kinds of metal-free systems were compared among themselves were also considered. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted independently and in duplicate. Trial authors were contacted for missing information. Available results for the outcomes of interest of the systematic review of the studies included were tabulated as they could not be included in a formal meta-analysis. MAIN RESULTS: Nine trials involving a total of 448 participants were included. We judged two trials to be at unclear risk of bias and seven to be at high risk of bias. The majority of items of risk of bias were evaluated to be at unclear or high risk level in more than 50% of the included trials. Each trial except two was addressing a different type of intervention. All evidence was rated as being of very low quality due to problems with risk of bias and imprecision of results, the latter being due to very small sample sizes, low event rates, 95% confidence intervals including the possibility of benefit for both the test and control groups, or combinations of these problems. This means that we are very uncertain about all of the results presented in this review.One trial compared metal-free single crowns (full contour zirconia) to cast gold single crowns in 224 participants and found insufficient evidence of a difference in failure rate after one year, but after five years there was some evidence of a benefit for the gold crowns. There was insufficient evidence of a difference for crown complications at either time of assessment.One trial compared three-unit metal-free FDPs (lithium disilicate) to three-unit metal-ceramic FDPs in 37 participants. There was insufficient evidence of a difference in bridge failure at one and six years, but some evidence of a benefit for the lithium disilicate group in terms of bridge complications at six years. One trial compared zirconia-ceramic FDPs to metal-ceramic FDPs in 34 participants but found insufficient evidence of a difference in bridge failures (i.e. no failures in either treatment group), bridge complications or patients' aesthetic evaluation at any time of assessment up to three years.One trial compared metal-free cantilevered FDPs to metal-ceramic cantilevered FDPs in 21 participants. There was insufficient evidence of a difference for any primary outcome: bridge failures (i.e. no failures in either treatment group), bridge complications, or patients' aesthetic evaluation at any time of assessment up to three years.One trial compared metal-free implant-supported screw retained single crowns (zirconia veneered with feldspathic ceramic) to metal-ceramic implant-supported screw-retained single crowns in 20 participants. There was insufficient evidence of a difference for any primary outcome: crown failures (i.e. no failures in either treatment group), crown complications, or satisfaction/aesthetic evaluation at any time of assessment up to two years.Two trials compared metal-free implant abutments (zirconia) to metal implant abutments both supporting single crowns in 50 participants. There was insufficient evidence of a difference in abutment failure at one year.One trial compared metal-free implant-supported FDPs made of two different types of zirconia ceramic in 18 participants. There was insufficient evidence of a difference in failures at any time of assessment up to 10 years (i.e. no failures in either treatment group). There was some evidence of a benefit for the zirconia-toughened alumina group in terms of complications (chipping).One trial compared metal-free tooth-supported FDPs made with two different veneering techniques (pressed versus layered) in 40 participants. There was insufficient evidence of a difference for failures (i.e. no failures in either treatment group) or complications at any time of assessment up to three years. AUTHORS' CONCLUSIONS: There is insufficient evidence to support or refute the effectiveness of metal-free materials for fixed prosthodontic treatment over metal-ceramic or other type of standard restorations. The overall quality of existing evidence was very low, therefore great caution should be exercised when generalising the results of the included trials. Until more evidence becomes available clinicians should continue to base decisions on which material to use for fixed prosthodontic treatment on their own clinical experience, whilst taking into consideration the individual circumstances and preferences of their patients. There is urgent need of properly designed RCTs.

[The dependence of the marginal adaptation of composite fillings in caries cavities of class ii by black, on the state of oral hygiene and intensity of caries].

INTRODUCTION: The problem of treatment of dental caries by fillings in dentistry is the key point in dentistry. Thus the main issue is the long-term functioning of the restorations. Particularly acute, this problem in the reduction of cavities class II according to Black, where the pressure on the filling is sufficiently high. MATERIALS AND METHODS: It was examined and treated 87 patients with different levels of oral hygiene of oral cavity and caries of varying intensity and whom 186 defects of hard tissues of teeth class II Black were fitted. All patients were divided into 3 groups depending on the type of filling material selected. Each group was in turn divided into two groups depending on the type of the prepared cavity. In a subgroup (1) the preparation was carried out without additional primary cavity retention elements. In a subgroup (2) the preparation was carried out with the main cavity in the form of retention elements as extra place on the chewing surface. RESULTS: Analyzing the quality of edge adjacent of fillings and restorations in the long-term period (24 months) depending on the intensity of caries and oral hygiene, we found that the best results were obtained in patients with low intensity of caries, and in patients with a high level of oral hygiene of patients in all study groups. CONCLUSION: The best results in the short and long-term periods were obtained in II and IІІ groups. It should be noted that these groups the particularity of preparation has no influence on the quality of the restoration. According to restorations of group I where the restorative material was composite material as chemical hardening"Charisma PPF" ( "Heraeus Kulser"), this relation takes place. The best results in the short and long-term periods shown those restorations, under which created at preparing retention elements in the form of extra place.

Zirconia-based versus metal-based single crowns veneered with overpressing ceramic for restoration of posterior endodontically treated teeth: 5-year results of a randomized controlled clinical study.

OBJECTIVES: The aim of this 5-year randomized controlled trial was to compare the longevity and clinical behavior of single posterior crowns made with pressable ceramic on zirconia and on metal frameworks, and if failures occur, to delineate the contributing factors. METHODS: 72 patients, who needed the covering of at least a molar and/or premolar, were included in the study. All teeth were endodontically treated, with absence of periapical lesion or active periodontitis. Ninety single crowns were made with zirconia or metal framework and covered with pressable veneering ceramics. Two independent examiners assessed the survival of restorations at 6 months, 1-4 and 5 years after restoration placement including periapical radiographs, intraoral photographs, and USPHS modified criteria. The statistical analyses were performed with the Kaplan-Meier method. RESULTS: One core fracture occurred in Zircad/Zirpress crowns and one metal ceramic crown was lost for root fracture. Chipping fracture of the veneering ceramic was detected in 2 metal-ceramic crowns and in 3 zirconia-based crowns. The Estimate Cumulative Survival (ECS) and the Estimate Cumulative Success (ECSs) with standard deviation (SE) were respectively 97,73±2,19 and 92,64±4,14 for zirconia-based crowns whereas 97,44±2,39 and 91,11±4,27 for porcelain fused to metal crowns. CONCLUSIONS: The present randomized controlled trial shows that the survival of zirconia-based and metal-based single crowns is similar over a follow-up period of 5 years. No significant differences in esthetic, functional and biological outcomes were demonstrated between the two groups. The main failure mode was the chipping fracture of the veneering ceramic in both materials. Study number on ClinicalTrial.gov NCT02758457. CLINICAL SIGNIFICANCE: According to the results of this clinical study, zirconia-based rehabilitations with overpressing veneering technique represent a valid alternative to metal-based for posterior single crown restorations.

Comportamento mecânico de instrumentos WaveOne e ProTaper em relação à torção, dureza e tenacidade / Mechanical properties of WaveOne and ProTaper instruments in relation to torsion, hardness and toughness

Objetivo: esse estudo teve como objetivo avaliar a resistência à fratura por torção de duas marcas de instrumentos mecanizados de NiTi, com formas geométricas distintas e produzidas por ligas metálicas diferentes. Métodos: quinze instrumentos WaveOne Large e quinze ProTaper F4 foram selecionados e submetidos aos ensaios mecânicos de torção, microdureza Vickers e tenacidade. No ensaio de torção, foram avaliados a deformação angular até a fratura e o torque máximo. As superfícies fraturadas e as hastes helicoidais dos instrumentos foram analisadas por meio de microscopia eletrônica de varredura (MEV). Resultados: os valores do ângulo máximo em torção foram maiores para o ProTaper, enquanto o torque máximo em torção (N/cm) foi maior para o WaveOne. Os valores de microdureza Vickers foram maiores para a liga NiTi M-Wire, enquanto o grupo controle apresentou maior tenacidade. O teste t de Student demonstrou diferença significativa nos ensaios de torção (p < 0,05), tenacidade e microdureza Vickers. A análise do MEV revelou deformação plástica ao longo das hélices helicoidais de todos os instrumentos fraturados e fratura tipo dúctil. Conclusão: os instrumentos fabricados em NiTi M-Wire apresentaram maior resistência à fratura por torção e maior microdureza, em comparação aos de NiTi convencional. Devido ao maior ângulo de torção do ProTaper e à maior deformação até a fratura, esses parâmetros tornam esse instrumento mais seguro do ponto de vista clínico.

Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

BACKGROUND/PURPOSE: Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. METHODS: A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. RESULTS: The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. CONCLUSION: The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure.

Clinical Acceptability of the Internal Gap of CAD/CAM PD-AG Crowns Using Intraoral Digital Impressions.

The purpose of this study was to compare the internal gap between CAD/CAM palladium-silver crowns and cast gold crowns generated from intraoral digital versus conventional impressions and to determine the clinical acceptability. Nickel-chrome master dies were made from the prepared resin tooth with the conventional impression method (n = 40). For ICC (Intraoral, CAD/CAM) group, 10 intraoral digital impressions were made, and 10 CAD/CAM crowns of a PD-AG (palladium-silver) machinable alloy were generated. For IC (Intraoral, Cast) group, 10 gold crowns were cast from ten intraoral digital impressions. For CCC (Conventional, CAD/CAM) group, 10 CAD/CAM PD-AG crowns were made using the conventional impression method. For CC (Conventional, Cast) group, 10 gold crowns were fabricated from 10 conventional impressions. One hundred magnifications of the internal gaps of each crown were measured at 50 points with an optical microscope and these values were statistically analyzed using a two-way analysis of variance (α = 0.05). The internal gap of the intraoral digital impression group was significantly larger than in the conventional impression group (P < 0.05). No significant difference was observed between the CAD/CAM group and the cast group (P > 0.05). Within the limitations of this in vitro study, crowns from intraoral digital impressions showed larger internal gap values than crowns from conventional impressions.

WITHDRAWN: Dental fillings for the treatment of caries in the primary dentition.

BACKGROUND: Childhood caries (tooth decay) consists of a form of tooth decay that affects the milk teeth (also known as baby or primary teeth) of children. This may range from tooth decay in a single tooth to rampant caries affecting all the teeth in the mouth. Primary teeth in young children are vital to their development and every effort should be made to retain these teeth for as long as is possible. Dental fillings or restorations have been used as an intervention to repair these damaged teeth. Oral health professionals need to make astute decisions about the type of restorative (filling) material they choose to best manage their patients with childhood caries. This decision is by no means an easy one as remarkable advances in dental restorative materials over the last 10 years has seen the introduction of a multitude of different filling materials claiming to provide the best performance in terms of durability, aesthetics, symptom relief, etc when placed in the mouth. This review sought to compare the different types of dental materials against each other for the same outcomes. OBJECTIVES: The objective of this review was to compare the outcomes (including pain relief, survival and aesthetics) for restorative materials used to treat caries in the primary dentition in children.  Additionally, the restoration of teeth was compared with extraction and no treatment. SEARCH METHODS: Electronic searches of the following databases were undertaken: the Cochrane Oral Health Group's Trials Register (up to January 2009); CENTRAL (The Cochrane Library 2009, Issue1); MEDLINE (1966 to January 2009); EMBASE (1996 to January 2009); SIGLE (1976 to 2004); and conference proceedings on early childhood caries, restorative materials for paediatric dentistry, and material sciences conferences for dental materials used for children's dentistry (1990 to 2008). The searches attempted to identify all relevant studies irrespective of language.Additionally, the reference lists from articles of eligible papers were searched, handsearching of key journals was undertaken, and personal communication with authors and manufacturers of dental materials was initiated to increase the pool of suitable trials (both published and unpublished) for inclusion into this review. SELECTION CRITERIA: Randomised controlled trials (RCTs) or quasi-randomised controlled trials with a minimum period of 6 months follow up were included. Both parallel group and split-mouth study designs were considered. The unit of randomisation could be the individual, group (school, school class, etc), tooth or tooth pair. Included studies had a drop-out rate of less than 30%. The eligible trials consisted of young children (children less than 12 years) with tooth decay involving at least one tooth in the primary dentition which was symptomatic or symptom free at the start of the study. DATA COLLECTION AND ANALYSIS: Data were independently extracted, in duplicate, by two review authors. Disagreements were resolved by consultation with a third review author. Authors were contacted for missing or unclear information regarding randomisation, allocation sequence, presentation of data, etc. A quality assessment of included trials was undertaken. The Cochrane Collaboration statistical guidelines were followed for data analysis. MAIN RESULTS: Only three studies were included in this review. The Fuks 1999 study assessed the clinical performance of aesthetic crowns versus conventional stainless steel crowns in 11 children who had at least two mandibular primary molars that required a crown restoration. The outcomes assessed at 6 months included gingival health (odds ratio (OR) 0.3; 95% confidence interval (CI) 0.01 to 8.32), restoration failure (OR 3.29; 95% CI 0.12 to 89.81), occlusion, proximal contact and marginal integrity. The odds ratios for occlusion, proximal contact and marginal integrity could not be estimated as no events were recorded at the 6-month evaluation. The Donly 1999 split-mouth study compared a resin-modified glass ionomer (Vitremer) with amalgam over a 36-month period. Forty pairs of Class II restorations were placed in 40 patients (21 males; 19 females; mean age 8 years +/- 1.17; age range 6 to 9 years). Although the study period was 3 years (36 months), only the 6- and 12-month results are reported due to the loss to follow up of patients being greater than 30% for the 24- and 36-month data. Marks 1999a recruited 30 patients (age range 4 to 9 years; mean age 6.7 years, standard deviation 2.3) with one pair of primary molars that required a Class II restoration. The materials tested were Dyract (compomer) and Tytin (amalgam). Loss to follow up at 24 and 36 months was 20% and 43% respectively. This meant that only the 24-month data were useable. For all of the outcomes compared in all three studies, there were no significant differences in clinical performance between the materials tested.No studies were found that compared restorations versus extractions or no treatment as an intervention in children with childhood caries. AUTHORS' CONCLUSIONS: It was disappointing that only three trials that compared three different types of materials were suitable for inclusion into this review. There were no significant differences found in all three trials for all of the outcomes assessed. Well designed, randomised controlled trials comparing the different types of filling materials for similar outcomes are urgently needed in dentistry. There was insufficient evidence from the three included trials to make any recommendations about which filling material to use.

Implant survival and patient satisfaction of reduced diameter implants made from a titanium-zirconium alloy: A retrospective cohort study with 550 implants in 311 patients.

The aim of the study was to evaluate implant survival of reduced-diameter implants compared to regular-diameter implants. A retrospective evaluation of 154 Straumann Bone Level Roxolid® implants (diameter 3.3 mm) with SLActive®-surface in 107 patients, which were inserted between 2009 and 2010 in private practice, was performed. The mean observation period was 22.4 ± 8.2 months. 396 Straumann SLActive® implants (4.1 mm and 4.8 mm) in 204 patients, with an observation period of 28.4 ± 10.1 months served as control group. Implant survival rate, resonance frequency analysis and patient satisfaction were evaluated. The implant survival rate was 97.4% in the test vs. 98.5% in the control group. Resonance frequency analysis showed statistically significant lower values for the reduced-diameter implants. Patient satisfaction showed no significant difference between the test and the control group. Reduced-diameter implants displayed high survival rates during the period investigated and represent a convincing treatment alternative. Long-term follow-up investigations confirmed the high implant survival rates of 96.8% (after 69.7 ± 12.3 months) in the test group and 98.5% (after 76.0 ± 13.6 months) in the control group.

Adjunctive Steps for Disinfection of the Mandibular Molar Root Canal System: A Correlative Bacteriologic, Micro-Computed Tomography, and Cryopulverization Approach.

INTRODUCTION: This study evaluated the disinfecting ability of chemomechanical preparation with rotary nickel-titanium instruments, followed by 2 distinct adjunctive procedures in the root canals of extracted mandibular molars by means of a correlative analytical approach. METHODS: Twenty-two extracted mandibular molars were selected and anatomically matched between groups on the basis of micro-computed tomographic analysis. In the first phase of the experiment, root canals were contaminated with Enterococcus faecalis and subjected to chemomechanical preparation with BT RaCe instruments and 2.5% NaOCl irrigation. Then either XP-Endo Finisher instrument or passive ultrasonic irrigation was used to supplement disinfection. Micro-computed tomography was used to show whether the percentage of unprepared areas correlated to bacterial counts. In the second phase, the same teeth were contaminated once again, and the adjunctive procedures were used. Samples from the isthmus area of mesial roots and the apical 5-mm fragment of distal roots were obtained by cryopulverization. Samples taken before and after treatment steps in both phases were evaluated by quantitative polymerase chain reaction and statistically analyzed. RESULTS: In phase 1, preparation in both groups resulted in substantial decrease of bacterial counts (P < .001). The adjunctive approaches led to a further small bacterial reduction, which was significant for XP-Endo Finisher (P < .05). No significant differences were observed between groups for persisting bacterial counts. Correlative analysis revealed no statistically significant relationship between bacterial reduction and the percentage of unprepared areas (P > .05). In phase 2, both methods had significant antibacterial effects in the main canal, but none of them could predictably disinfect the isthmus/recess areas. CONCLUSIONS: Both XP-Endo Finisher and passive ultrasonic irrigation exhibited antibacterial effectiveness, but only the former caused a significant reduction in the bacterial counts after chemomechanical preparation. None of them were effective in predictably disinfecting the isthmus/recess areas.

[The use of Foley catheter in reconstructive procedures involving the middle third of the facial skeleton].

The aim of this study was to improve the efficiency of surgical treatment of patients with fractures involving zygomatico-orbital complex and maxillary sinus through the use of Foley catheter. 352 patients with fractures of the middle third of the facial skeleton were treated at the Departments of Oral & Maxillofacial Surgery in Novokuznetsk Institute and I.M. Sechenov First MSMU. All patients underwent open reduction and osteosynthesis using extramedullary titanium mini-plates and NiTi mini-clamps. In the cases with large bone defects additional reconstructive techniques were used such as replantation of bone fragments and endoprosthesis with NiTi implants. For the purpose of drainage and retention Foley catheter was placed in the cavity of the maxillary sinus after the surgical procedure. We obtained good and satisfactory results in the majority of clinical cases. The use of Foley catheter was found to be very effective for the post-operative drainage and hemostasis of the maxillary sinus and in cases involving the use of fixation implant in the reconstructive surgeries in the middle third of the face.

Survival of cast-metal, resin-bonded fixed partial dental prostheses after nearly 20-year follow-up: A retrospective study.

STATEMENT OF PROBLEM: Cast-metal resin-bonded fixed partial dental prostheses (RBFPDPs) are a conservative approach to replacing missing teeth. Despite their recognized advantages, the use of cast-metal RBFPDPs as a definitive option remains somewhat controversial because of the lack of long-term studies on their success. PURPOSE: The purpose of this retrospective study was to evaluate the long-term survival rate of cast-metal RBFPDPs and investigate the influence of covariates such as sex, type of prosthesis, location, number of pontics, abutments, and type of luting cement on the survival of bonded prostheses. MATERIAL AND METHODS: This study evaluated 209 cast-metal RBFPDPs cemented in 181 patients (mean 41.06 ±11.90 years of age) treated in the principal author's private practice between July 1993 and May 2012. Data sheets were completed at the patients' recall examination at regular intervals or if seen for complications. Kaplan-Meier analysis was used to evaluate the survival rate of the prostheses before debonding. The Cox model and Wald test were used to analyze the prognostic factors (α=.05). RESULTS: A total of 198 prostheses were studied. Eleven cast-metal RBFPDPs were lost to follow-up. This study evaluated the effect of different variables on the survival rate of both conventional RBFPDPs (wing-wing) and combination resin-bonded FPDPs (wing-crown) types. Survival rate was divided into "with repair" and "without repair" groups. The mean survival time was 102.24 months for the group with no repair and 119.76 months for the group with repair. The survival rate after 5, 10, and 15 years was 86%, 42%, and 15% with repair, whereas 69%, 32%, and 14% of the prostheses survived without repair. CONCLUSIONS: In appropriate clinical conditions and selected patients, cast-metal RBFPDPs were a viable treatment option with an acceptable survival rate.

Surface properties of Ti-35Nb-7Zr-5Ta: Effects of long-term immersion in artificial saliva and fluoride solution.

STATEMENT OF PROBLEM: The mechanical properties of new titanium alloys with an elastic modulus closest to cortical bone have been studied. However, potentially damaging conditions experienced in the oral cavity, such as fluoride ions, can initiate a localized or crevice process of corrosive degradation in the alloy surfaces. PURPOSE: The purpose of this in vitro study was to evaluate the effects of long-term immersion in artificial saliva or in fluoride solution on mean roughness (Ra), Vickers hardness, and topography of the new titanium alloy Ti-35Nb-7Zr-5Ta (TNZT) compared with those of cp Ti and Ti-6Al-4V (TAV). MATERIAL AND METHODS: Disks (N=210) were divided into cp Ti, TAV, and TNZT and subdivided according to the following treatments: no immersion (N(-), control), immersion in artificial saliva (S), and immersion in fluoride (F) during periods equivalent to 5, 10, 15, and 20 years. The Ra and Vickers hardness were measured with a profilometer and a hardness tester. The topography was analyzed by scanning electronic microscopy. Data were compared using the Kruskal-Wallis and Dunn tests (α=.05). RESULTS: Values of Ra and hardness were significantly different among the metals (Ra: TAV

Clinical evidence on titanium-zirconium dental implants: a systematic review and meta-analysis.

The use of titanium implants is well documented and they have high survival and success rates. However, when used as reduced-diameter implants, the risk of fracture is increased. Narrow diameter implants (NDIs) of titanium-zirconium (Ti-Zr) alloy have recently been developed (Roxolid; Institut Straumann AG). Ti-Zr alloys (two highly biocompatible materials) demonstrate higher tensile strength than commercially pure titanium. The aim of this systematic review was to summarize the existing clinical evidence on dental NDIs made from Ti-Zr. A systematic literature search was performed using the Medline database to find relevant articles on clinical studies published in the English language up to December 2014. Nine clinical studies using Ti-Zr implants were identified. Overall, 607 patients received 922 implants. The mean marginal bone loss was 0.36±0.06mm after 1 year and 0.41±0.09mm after 2 years. The follow-up period ranged from 3 to 36 months. Mean survival and success rates were 98.4% and 97.8% at 1 year after implant placement and 97.7% and 97.3% at 2 years. Narrow diameter Ti-Zr dental implants show survival and success rates comparable to regular diameter titanium implants (>95%) in the short term. Long-term follow-up clinical data are needed to confirm the excellent clinical performance of these implants.

Electrochemical impedance investigation of Ni-free Co-Cr-Mo and Co-Cr-Mo-Ni dental casting alloy for partial removable dental prosthesis frameworks.

STATEMENT OF PROBLEM: The pH level of the oral environment influences corrosion in dental materials. Corrosion behaviors of Co-Cr-Mo and Co-Cr-Mo-Ni alloys in different pH environments remain undetermined. PURPOSE: The purpose of this in vitro study was to evaluate the surface properties and corrosion behaviors of Co-Cr-Mo and Co-Cr-Mo-Ni dental casting alloys in artificial saliva at pH values of 5.0 and 2.5. MATERIAL AND METHODS: Fifty specimens were divided into 2 groups according to the alloy composition. The surface compositions, hardness values, and microstructures of the alloys were measured before immersion in artificial saliva. The corrosion behaviors of the specimens in artificial saliva at pH values of 5.0 and 2.5 were studied using electrochemical impedance spectroscopy (EIS). The microstructures were examined again after a 7-day immersion test. Data were analyzed by a 1-way analysis of variance (ANOVA) test (α=.05). RESULTS: As expected, the relative levels of Co and Cr of the surface composition were higher in the Co-Cr-Mo alloy. The Co-Cr-Mo alloy had statistically higher surface hardness than the Co-Cr-Mo-Ni alloy (P<.05). In the pH 2.5 environment, both of the alloys showed decreased corrosion resistance (P<.05). The microstructure of the Co-Cr-Mo-Ni alloy corroded more than that of the Co-Cr-Mo alloy in the pH 2.5 environment. The oxide-layer corrosion resistance of the Co-Cr-Mo alloy was better than that of the Co-Cr-Mo-Ni alloy in Fusayama artificial saliva solutions at pH values of both 5.0 and 2.5 (P<.05). CONCLUSIONS: The corrosion resistance of the Co-Cr-Mo alloy was better in the oral environment, especially at a low pH value.

Clinical evaluations of cast gold alloy, machinable zirconia, and semiprecious alloy crowns: A multicenter study.

STATEMENT OF PROBLEM: Few studies have compared the marginal and internal fits of crowns fabricated from machinable palladium-silver-indium (Pd-Ag-In) semiprecious metal alloy. PURPOSE: The purpose of this clinical study was to evaluate and compare the marginal and internal fits of machined Pd-Ag-In alloy, zirconia, and cast gold crowns. MATERIAL AND METHODS: A prospective clinical trial was performed on 35 participants and 52 abutment teeth at 2 centers. Individuals requiring prosthetic restorations were treated with gold alloy or zirconia crowns (2 control groups) or Pd-Ag-In alloy crowns (experimental group). A replica technique was used to evaluate the marginal and internal fits. The buccolingual and mesiodistal cross-sections were measured, and a noninferiority comparison was conducted. RESULTS: The mean marginal gaps were 68.2 µm for the gold crowns, 75.4 µm for the zirconia crowns, and 76.9 µm for the Pd-Ag-In alloy crowns. In the 5 cross-sections other than the distal cross-section, the 2-sided 95% confidence limits for the differences between the Pd-Ag-In alloy crowns and the 2 control groups were not larger than the 25-µm noninferiority margin. The control groups displayed smaller internal gaps in the line angle and occlusal spaces compared with the Pd-Ag-In crown group. CONCLUSION: The marginal gaps of machinable Pd-Ag-In alloy crowns did not meet the noninferiority criterion in the distal margin compared with zirconia and gold alloy crowns. Nonetheless, all 3 crowns had clinically applicable precision.

Análise da resistência à fadiga flexural de instrumentos fabricados com a tecnologia CM após ensaios de flexão e ciclos de esterilização / Effect of bending and sterilization on the fatigue resistance of thermally treated nickel-titanium instruments

A tecnologia "Controlled Memory (CM)", que envolve o emprego de tratamentos térmicos em instrumentos já usinados, é uma das novas estratégias propostas pelos fabricantes de instrumentos endodônticos de NiTi para aumentar sua flexibilidade e resistência à fadiga. O objetivo desse trabalho foi avaliar a capacidade de recuperação de forma e a manutenção das propriedades mecânicas dos instrumentos Hyflex CM (HF; Coltene/Whaledent, USA) e Typhoon CM (TYP; Clinician's Choice Dental Products, USA), de diâmetro e conicidade 30/.06, após serem submetidos a ciclos de flexão até 45º (especificação ISO 3630-1) e esterilização em autoclave. Dez instrumentos de cada sistema foram submetidos a dobramento a 45º, esterilizados em autoclave a 134° por 20 minutos e fotografados com uma câmera de alta resolução em lupa estereoscópica, para mensuração da deformação residual. Foram realizados cinco ciclos de flexão, alternados com ciclos de esterilização. As imagens foram analisadas no software Image J 1.48V. O número médio de ciclos até a fratura por fadiga (Nf) de instrumentos novos e de instrumentos submetidos à flexão e esterilização foi obtido em um dispositivo de bancada que simula um canal curvo. Ambos os instrumentos apresentaram valores semelhantes de momento de dobramento a 45º (Mb45) (p=0,239) e verificou-se uma redução nestes valores após os ciclos de flexão e esterilização, porém com resultado estatístico apenas para HF (p=0,005). Quando submetidos à esterilização, os instrumentos HF recuperaram totalmente sua forma inicial reta, ao contrário dos instrumentos TYP (p=0,000), que apresentaram deformação residual média em torno de 2,7º. Instrumentos TYP submetidos a cinco ciclos de flexão e esterilização apresentaram queda na sua resistência à fadiga (p=0,006), o que não ocorreu com HF (p=0,825). Os instrumentos avaliados no presente trabalho, embora produzidos empregando tratamentos térmicos referenciados como tecnologia CM, apresentaram capacidade de recuperação de forma e resistência à fadiga distintas

The use of Controlled Memory technology involving the heat treatment of machined NiTi instruments is among the new strategies manufacturers have developed to improve files' fatigue resistance and flexibility. The aim of this study was to evaluate the shape recovery capacity and maintenance of mechanical properties of Hyflex CM (HF; Coltene/Whaledent, USA) and Typhoon CM (TYP; Clinician's Choice Dental Products, USA) after being submitted to bending at 45°, sterilization and fatigue stresses. Ten instruments from each brand were submitted to the 45° bending test, according specification ISO 3630-1, autoclaved at 134°C for 20 minutes and photographed with a high resolution camera and with magnification to check whether all files have returned to their original shape. The images were analyzed in the software Image J 1.48V. In order to reproduce the clinical practice, five bending cycles were alternated with sterilization cycles. The average number of cycles until failure (Nf) were obtained for new instruments and instruments submitted to bend and sterilization in a bench device that simulates a curved canal. Both brands presented similar values of bending moments at 45º (Mb45) (p=0,239). A decrease in this values were verified after the five cycles of bending and sterilization, however only statistically relevant for HF instruments (p= 0,005). When submitted to sterilization, all HF instruments recovered their original shape. On the other hand, a significant number of TYP instruments were shown to be plastically deformed (p= 0,000) with an average residual deformation of 2,7°. TYP instruments submitted to five cycles of bending and sterilization presented a statistically significant decrease in their Nf (p=0,006), which did not occur to HF instruments (p=0,825). The two types of instruments tested in this study, although referenced as CM instruments, responded differently to thermal treatments applied during the manufacturing process and presents distinct shape recovery capacity and fatigue resistance

Biomechanical and Histomorphometrical Evaluation of TiZr Alloy Implants: An in vivo Study in the Rabbit.

BACKGROUND: Clinically, there is a demand for mechanically stronger alloyed implants; however, not much evidence exists with regard to these materials. PURPOSE: To test the osseointegration property of TiZr1317 implants in a rabbit model. MATERIALS AND METHODS: Hydrophilic titanium-zirconium alloy (TiZr1317) implants with sand-blasted and acid-etched surface (test) and hydrophilic cpTi implants with the same treatment (control) were placed pairwise in the hind limbs (two in each tibia and one in each femur) of 36 Swedish lop-eared rabbits. After 2, 4, and 12 weeks (n = 12/time point), the bone samples were subjected to removal torque (RTQ, proximal tibia and femur) and histologic/histomorphometric (distal tibia) testings. RESULTS: The control presented significantly higher RTQ than the test at 2 weeks (55 vs 36 Ncm). No differences were observed for other time points. The test presented higher mean BIC than the control (19.25 vs 13.89 %) at 4 weeks; however, there were no statistical differences for the following time point tested in vivo.The new bone area was significantly higher for the test at 4 weeks in the marrow areas. CONCLUSION: The TiZr1317 implants presented comparable biologic outcomes to that of the cpTi implants through a 12-week evaluation period.

Removal of filling materials from oval-shaped canals using laser irradiation: a micro-computed tomographic study.

INTRODUCTION: The aim of this study was to assess the efficacy of lasers in removing filling remnants from oval-shaped canals after retreatment procedures with rotary instruments using micro-computed tomographic imaging. METHODS: The root canals of 42 mandibular canines were prepared and obturated using the warm vertical compaction technique. Retreatment was performed with rotary instruments, and the specimens were distributed in 3 groups (n = 14) according to the laser device used in a later stage of retreatment procedure: Er:YAG, Er:YAG laser-based photon-induced photoacoustic streaming, and Nd:YAG. The specimens were scanned in a micro-computed tomographic device after root canal filling and each stage of retreatment at a resolution of 13.68 µm. The percentage differences of the remaining filling material before and after laser application within and between groups were statistically compared using the paired sample t test and 1-way analysis of variance test, respectively. Significance level was set at 5%. RESULTS: Overall, filling residues were located mainly in the apical third and into canal irregularities after the retreatment procedures. After using rotary instruments, the mean percentage volume of the filling remnants ranged from 13%-16%, with no statistical significant difference between groups (P > .05). Within groups, additional laser application had a significant reduction in the amount of the remaining filling materials (P < .05). A comparison between groups showed that Er:YAG laser application after the use of rotary instruments had a significantly higher removal of filling remnants (~13%) than Er:YAG laser-based photon-induced photoacoustic streaming (~4%) and Nd:YAG (~3%) (P < .05). CONCLUSIONS: None of the retreatment procedures completely removed the filling materials. The additional use of lasers improved the removal of filling material after the retreatment procedure with rotary instruments.