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The objective of this chapter is to summarize the criticisms of laboratory friction protocols that appeared in the last two decades through a critique of the research protocols employed, assessment of the clinical relevance of the results reported, and analysis of the main factors. From this summary, use of the in vitro approach is precluded as a reliable method for clarification of the impact of research findings at the clinical level. To this end, an analysis of the methodological approaches employed for the investigation of frictional effects during bracket sliding on wires raises a number of issues.

Statement of problem. The color of dental porcelain depends on the type of metal substrate. Little research has been done to document the effects of different types of high-palladium alloys on the color of dental porcelain. Purpose. The purpose of this in vitro study was to evaluate the effects of different high-palladium alloys on the resulting color of dentin porcelain, as well as on that of opaque porcelain after simulated dentin and glazing firing cycles. Material and methods. Three Pd-Cu-Ga alloys, Spartan Plus (S), Liberty (13), and Freedom Plus (F), and 5 Pd-Ga alloys, Legacy (L), IS 85 (1), Protocol (P), Legacy XT (X), and Jelenko No. 1 (N), were examined. A Pd-Ag alloy, Super Star (T), was included for comparison to the high-palladium alloys, and the Au-Pd alloy, Olympia (0), served as the control. Six cast discs (16 X I mm) were prepared from each of the alloys. Shade B I opaque porcelain (Vita-Omega) was applied at a final thickness of 0.1 mm. After 2 opaque porcelain firing cycles, the surfaces were airborne-particle abraded, and the specimens were divided into 2 groups. In the first group, 0.9 mm of B1 dentin porcelain was applied. The other group of specimens with only opaque porcelain underwent the same dentin porcelain and glazing firing cycles. Color differences (DeltaE) were determined with a colorimeter between the control and each experimental group, after the second opaque porcelain, second dentin porcelain, and glazing firing cycles. One-way analysis of variance and Dunnett’s multiple range test were performed on the DeltaE data (alpha=.05). Results. After the application of dentin porcelain, the 3 Pd-Cu-Ga alloys showed significantly different (P

The purpose of this study was to investigate the microstructure and bonding mechanisms for four types of ceramic brackets by using information from several methods. Two of the bracket provided exclusively micromechanical retention as a bonding mechanism, with the use of microspheres or microcrystals to achieve a rough structure for the bracket base. A silane layer that provided chemical adhesion was found to cover the bases of the two other types of brackets; one type also used central regions of increased roughness to provide additional micromechanical retention. Polarized-light optical microscopy showed that the silane layer was not continuous. Small area x-ray photoelectron spectroscopy analysis (SAXPS) of the silane layer was consistent with the presence of gamma-methacryloxypropyl trimethoxysilane. The study of the ceramic bracket bases revealed a wide variety in composition, structure, morphologic condition, and coating treatment that implies different bonding mechanisms to orthodontic adhesives.

The poor positioning of dental implants directly influences the functional and esthetic result of the implant-supported prosthesis. And as an alternative to correcting the positioning, prosthetic components such as prefabricated and customized abutments may be used. The current study aims to present an alternative resolution for malpositioned dental implants, with the hopes of minimizing damage to osseointegration and gingival tissues. A 53-year-old female patient had two implants in regions 11 and 21 with a height discrepancy of approximately 7 mm between them. The following treatment plan was proposed: the manufacture of two metal-free crowns and the use of a customized abutment to correct the height of the implant. A metal UCLA (Universal Long Castable Abutment) was used as a healer. The case includes 5 years of follow-up. It can be concluded that the use of a customized abutment as a prosthetic solution for an implant installed far below the cervical region of the tooth presented satisfactory esthetic and functional results with peri-implant bone maintenance and long-term gingival health.Descriptors: Dental Implantation; Dental Prosthesis, Esthetics, Dental.ReferênciasGoodacre CJ, Bernal G, Rungcharassaeng K, Kan JY. Clinical complications with implants and implant prostheses. J Prosthet Dent. 2003;90(2):121-32.Branemark PI, Hansson BO, Adell R, Breine U, Lindström J, Hallén O, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl. 1977;16:1-132.Simensen AN, Bøe OE, Berg E, Leknes KN. Patient knowledge and expectations prior to receiving implant-supported restorations. Int J Oral Maxillofac Implants. 2015;30(1):41-7.Hyland R, Ellis J, Thomason M, El-Feky A, Moynihan P. A qualitative study on patient perspectives of how conventional and implant-supported dentures affect eating. J Dent. 2009;37(9):718-23.Arunyanak SP, Pollini A, Ntounis A, Morton D. Clinician assessments and patient perspectives of single-tooth implant restorations in the esthetic zone of the maxilla: A systematic review. J Prosthet Dent. 2017;118(1):10-17. Higginbottom FL. Implants as an option in the esthetic zone. J Oral Maxillofac Surg. 2005; 63(9 Suppl 2):33-44.Moráguez OD, Vailati F, Belser UC. Malpositioned implants in the anterior maxilla: a novel restorative approach to reestablish peri-implant tissue health and acceptable esthetics. Part II: Case report and discussion. Int J Esthet Dent. 2015;10(4):522-32.Pelekanos S, Pozi di G, Kourtis S. Restoration of divergent implants with a 2-piece screw-retained fixed, complete dental implant prostheses. J Prosthet Dent. 2016;115(4):389-92.DeFuria C, Weber HP, Kudara Y, Papaspyridakos P. Management of a Malpositioned Implant in the Anterior Maxilla. Compend Contin Educ Dent. 2017;38(3):e9-e12.Scutellà F, Weinstein T, Lazzara R, Testori T. Buccolingual implant position and vertical abutment finish line geometry: two strictly related factors that may influence the implant esthetic outcome. Implant Dent. 2015;24(3):343-8.Funato A, Salama MA, Ishikawa T, Garber DA, Salama H. Timing, positioning, and sequential staging in esthetic implant therapy: a four-dimensional perspective. Int J Periodontics Restorative Dent. 2007;27(4):313-23.Pjetursson BE, Asgeirsson AG, Zwahlen M, Sailer I. Improvements in implant dentistry over the last decade: comparison of survival and complication rates in older and newer publications. Int J Oral Maxillofac Implants. 2014;29 Suppl:308-24.Fuentealba R, Jofré J. Esthetic failure in implant dentistry. Dent Clin North Am. 2015;59(1):227-46.Kim DG, Elias KL, Jeong YH, Kwon HJ, Clements M, Brantley WA, et al. Differences between buccal and lingual bone quality and quantity of peri-implant regions. J Mech Behav Biomed Mater. 2016;60:48-55.Arai K, Takeda Y, Mori Y, Terauchi R, Furumori T, Tanaka S, et al. Analysis of factors associated with maintenance discontinuation in implant patients. Springerplus. 2015;12;4:767.