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STATEMENT OF PROBLEM: The type of veneer preparation is often chosen according to the patient's tooth structure and occlusion. Taking biomechanics into account in this decision-making process provides the clinician with more technical information on how to improve the clinical longevity of restorations. However, biomechanical analyses of veneer preparation designs are sparse. PURPOSE: The purpose of this 3-dimensional (3D) finite element analysis with microcomputed tomography (µCT) data obtained from realistic models was to assess the influence of different preparations for ceramic and composite resin veneers on restoration and resin layer stress distribution. MATERIAL AND METHODS: Four replicas of a central incisor were printed and prepared for laminate veneers with 4 different incisal edge designs: shoulder (SH), palatal chamfer (PC), palatal chamfer and oblique fracture involving the distal angle (OF-PC), and palatal chamfer involving horizontal incisal fracture (IF-PC). After fabrication and cementation of the veneers, the restored replicas were assessed with µCT, and 3D finite element models were built. A 100-N load was applied on the palatal surface at 60 and 125 degrees relative to the longitudinal axis. Maximum principal stress and stress distribution on the veneers, cement layer, and tooth structure were calculated and analyzed. RESULTS: The SH preparation exhibited better stress distribution than the PC preparation, and the cement layer and the veneer were subjected to lower stress. The IF-PC preparation had better stress distribution than the OF-PC. The shoulder and IF-PC showed higher stress on laminate veneers, but lower stress on the cement layer. Ceramic veneers exhibited lower stress than composite resin veneers. CONCLUSIONS: The different incisal preparations for laminate veneers influenced stress distribution on restorations and on the resin cement layer. The shoulder type preparation showed better stress distribution and the composite resin veneers showed unfavorable results compared with the ceramic veneers.

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PURPOSE: To evaluate the effect of the triad finish line design, axial wall convergence angle, and luting cement on the marginal fit of metal copings used in metal-ceramic crowns. MATERIALS AND METHODS: Schematic dies and their respective copings were cast in NiCr alloy. The dies exhibited the following finish line/convergence angle combinations: sloping shoulder/6°, sloping shoulder/20°, shoulder/6°, shoulder/20°. Marginal fit was evaluated under a stereomicroscope, before and after cementation. Copings were air-abraded with 50 µm Al2 O3 particles and cemented with Cimento de Zinco, RelyX U100, or Panavia F cements (n = 10/group). Data were square-root transformed and analyzed by 3-way factorial random effect model and Tukey's post hoc test (α = 0.05). RESULTS: Statistical analysis showed significance for the interactions finish line and convergence angle (p < 0.05), convergence angle and time (p < 0.001), and luting cement and time (p < 0.001). Sloping shoulder/20° provided the highest marginal discrepancy when compared to the other finish line/convergence angle combinations, which were statistically similar among each other. For both convergence angles and for all luting cements, the marginal discrepancy was significantly higher after cementation. Before and after cementation, 6° provided better marginal fit than 20°. After cementation, Panavia F provided higher marginal discrepancy than Cimento de Zinco. CONCLUSION: Lower convergence angle combined with shoulder and a low-consistency luting cement is preferable to cement metal copings.

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Objetivo: rizogênese incompleta refere-se a dentes permanentes em que não houve a formação completa do ápice radicular, ocasionando perda da vitalidade pulpar e, consequentemente, incapacidade da bainha epitelial de Hertwig para induzir a formação completa da raiz. Devido ao traumatismo e escurecimento dental, se faz necessário em certos casos a confecção de coroas em porcelana pura para reabilitar a paciente em estética e função. O presente trabalho tem como objetivo demonstrar um caso de reabilitação estética e funcional em dente com rizogênese incompleta, onde se consideraram as perdas estruturais e alteração de cor, para que seja possível estabelecer o tratamento mais adequado. Relato de caso: paciente de 16 anos, gênero feminino, atendida na Clínica de Odontologia de uma instituição privada, insatisfeita com a estética do seu dente devido ao escurecimento do elemento 21, pois quando tinha 5 anos o dente foi traumatizado juntamente com o elemento 11. O plano de tratamento adotado para ambos os elementos foi a confecção de peças protéticas em porcelana e cimentação. Considerações finais: esse caso demonstrou que a confecção de coroas estéticas em porcelana é considerada uma boa conduta na rotina clínica em casos de escurecimento dental, devolvendo estética e função para o paciente.(AU)

Objective: incomplete rhizogenesis refers to permanent teeth with incomplete formation of the root apex, causing loss of pulp vitality and the consequent inability of the Hertwig epithelial sheath to induce complete root formation. Due to dental trauma and darkening, some cases require the production of pure porcelain crowns to rehabilitate the aesthetics and function of patients. The present study aims to show a case of aesthetic and functional rehabilitation in a tooth with incomplete rhizogenesis, in which structural losses and color change were considered to establish the most appropriate treatment. Case report: a 16-year-old female patient treated at the Dental Clinic of a private institution. The patient was not satisfied with the aesthetics of her tooth due to the darkening of element 21, because at 5 years old the tooth was traumatized along with element 11. The treatment used for both elements was the production of prosthetic porcelain crowns and cementation. Final considerations: this case showed that the production of aesthetic porcelain crowns is considered a good conduct in the clinical routine in cases of tooth darkening, returning aesthetics and function to the patient.(AU)

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A melhor maneira de se reproduzir um dente é mostrar as características anatômicas por todos os ângulos de observação. É muito importante saber reproduzir, expressar, fazer e entender a morfologia dental. Não existe um dente igual ao outro (mesmo nas mesmas classes dentais) e é preciso que um dente seja ideal de acordo com a cavidade bucal, com os lábios e a face. Existem várias técnicas e maneiras para se expressar isso. Para se ter essa "técnica" é preciso dedicação. A repetição do fazer aliado ao conhecimento teórico levam à reprodução da morfologia dental natural. Quando tudo isso se harmoniza na cavidade bucal, a reparação estética torna-se equilibrada, coesiva e funcional. Em outras palavras, para reproduzir o formato natural de um dente verdadeiro, é importante ou essencial o conhecimento da anatomia, da função e da integração dessas ao sorriso do paciente. Para que a reprodução chegue à perfeição, são necessários o treinamento assíduo e o estudo orientado. A anatomia dental envolve traçados que precisam ser desmistificados e outros que necessitam ser calculados e o estudo das faces de um dente determina um aprimoramento do conhecimento necessário à construção de trabalhos protéticos.

The best way to reproduce a tooth is to show the anatomical characteristics from all observation angles. It is very important to know how to reproduce, present, make and understand dental morphology. There are no equal teeth (even in the same dental classes) and it is necessary for a tooth to be ideal according to oral cavity, lips and face. There are several techniques and ways to express it. In order to have such "technique" it is necessary a great effort. Constant practice and technical knowledge takes to natural dental morphology reproduction. When all this is coordinated in the oral cavity, aesthetic repair becomes balanced, cohesive and functional. In other words, to reproduce the natural shape of a real tooth, it is important or essential anatomy and function knowledge, and the integration of these to the patient smile. For reproduction to come to perfection, frequent training and guided study are required. Dental anatomy involves tracings that have to be demystified and others that must be calculated and tooth faces study determines necessary knowledge improvement for the construction of prosthetic work

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STATEMENT OF PROBLEM: Factors that may affect the marginal adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) restorations include preparation design, impression technique, and CAD-CAM system. The influence of impression technique and preparation design on CAD-CAM partial coverage restorations has not been fully addressed. PURPOSE: The purpose of this in vitro study was to investigate the influence of direct and indirect digital scanning techniques and 2 preparation designs on the marginal adaptation of CAD-CAM onlays. MATERIAL AND METHODS: Two mesio-occlusal buccal onlay preparations with reduction of the mesiobuccal cusp were made: conventional preparation (CP) with a 1.2-mm modified shoulder margin and modified preparation (MP) flat cuspal reduction without shoulder. Virtual models were generated from each preparation by using a digital scanner (BlueCam; Dentsply Sirona) from the plastic teeth (direct digital scan) or from the stone dies (indirect digital scan). Onlays were designed using a CAD-CAM system (CEREC 4.0; Dentsply Sirona), and nanoceramic resin blocks (Lava Ultimate Restorative; 3M ESPE) were milled using the CEREC MCX milling machine. Marginal discrepancy was evaluated using an optical stereomicroscope at ×25 magnification in 18 locations distributed along the margins of the preparation. The data were analyzed by using 3-way ANOVA followed by the Tukey HSD test (α=.05). RESULTS: CP presented a statistically significant reduced average marginal adaptation (59 ±50 µm) than did MP (69 ±58 µm) (P<.001). The Tukey HSD test showed the presence of a significantly larger marginal discrepancy in the mesial and buccal locations of MP when compared with CP. Regarding impression techniques, the buccal location presented the smallest average marginal discrepancy in restorations fabricated with indirect impression when compared with direct impression (42 ±33 µm and 60 ±39 µm) (P<.001). CONCLUSIONS: The results showed that conventional preparation with a modified shoulder margin presented improved marginal adaptation compared with modified preparation with flat cuspal reduction. Direct and indirect digital scanning techniques produced restorations within a clinically acceptable range; however, the indirect scanning technique resulted in the fabrication of restorations with superior marginal adaptation on the buccal location.

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The purpose of this study was to describe and characterize (using the tensile test) an alternative handling technique for calcium hydroxide cement in temporary crown cementation. In the group treated with the conventional technique (n=10), the base and catalyst pastes of a calcium hydroxide cement (Dycal) were dispensed at a 1:1 ratio and mixed. The cement was then applied to the internal cervical surfaces of the provisional restoration, and the restoration was placed on the prepared tooth and kept in place with digital pressure. In the group treated with the alternative technique (n=10), the base paste of the calcium hydroxide cement (Dycal) was placed on the tooth and the catalyst paste was inserted into the temporary crown.The provisional prosthesis was placed on the tooth and kept in place with digital pressure. Tensile values were evaluated and compared between groups using Student's t test with a 5% level of significance (α = 0.05). Use of this alternative technique resulted in significantly lower tensile strength compared to the conventional technique (0.58 ± 0.12 vs. 1.08 ± 0.13 MPa; p<0.001). The technique presented here (alternative) could avoid the undesired removal of cemented cast posts or cores at the time of provisional prosthesis removal and ensures the cementation of extensive provisional prostheses with calcium hydroxide cement.

O objetivo deste estudo foi descrever e caracterizar (utilizando o ensaio de tração) uma técnica alternativa de manuseio para o cimento de hidróxido de cálcio na cimentação de coroa temporária. No grupo tratado com a técnica convencional (n=10), as pastas base e catalisadora de um cimento de hidróxido de cálcio (Dycal) foram dispensadas na proporção de 1:1 e misturadas. O cimento foi entao aplicado as superficies cervicais internas da restauração provisória, e a restauração foi colocada sobre o dente preparado e mantido no local com pressao digital. No grupo tratado com a técnica alternativa (n=10), a pasta base do cimento de hidróxido de cálcio (Dycal) foi colocada no dente e a pasta catalítica foi inserida na coroa provisória. A prótese provisória foi colocada sobre o dente e mantida no local com pressao digital. Os valores de tração foram avaliados comparados entre os grupos pelo teste t de Student, com nivel de significancia de 5% (α = 0,05). O uso desta técnica alternativa resultou em resistência à tração significativamente menor em comparação com a técnica convencional (0,58 ± 0,12 vs. 1,08 ± 0,13 MPa; p <0,001). A técnica aqui apresentada (alternativa) poderia evitar a remoção indesejada de pinos ou núcleos fundidos no momento da remoção da prótese provisória e garantir a cimentação de próteses provisórias extensas com cimento de hidróxido de cálcio.

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Devido à importância da realização de preparos com conicidade adequada, procurou- -se através desse trabalho de pesquisa mensurar a habilidade de alunos de graduação em Odontologia de reproduzir as corretas inclinações dos preparos. Foram avaliados sessenta e sete dentes artificiais preparados em manequins odontológicos por alunos, sendo G1: incisivo central superior direito (n=28), G2: canino superior direito (n=27) e G3: segundomolar inferior direito (n=12). Os ângulos de convergência mesio-distal e vestíbulo-lingual/palatino de cada preparado foram medidos com auxílio do microscópio digital Dino Lite. Os dados obtidos mostraram que os grupos G1 e G2 apresentam maiores valores de conicidade no sentido vestíbulo-lingual, enquanto o G3 apresenta maiores valores de conicidade no sentido mesio- -distal. Os dados da presente pesquisa corroboram com resultados encontrados na literatura, uma vez que que os valores de conicidade são maiores que os preconizados na literatura e através do questionário se observou que houve assimilação de conhecimento teórico em relação ao preparo de dentes, favorecendo a tomada de decisões quanto à adequação dos métodos de ensino da disciplina de Prótese Fixa da presente Instituição de Ensino Superior (AU).

Due to the importance of conducting preparations with adequate conicity, this research aimed to measure the ability of undergraduate dentistry students to reproduce the correct inclinations of preparations. Sixty-seven artificial teeth prepared on mannequins by the students were evaluated, G1: maxillary right central incisor (n=28), G2: upper right canine (n=27) and G3: lower right second molar (n=12). The convergence angles of mesial-distal and vestibular- -lingual/palatal of each preparation were measured with the aid of Dino Lite digital microscope. The data obtained showed that groups G1 and G2 presented higher conicity values ​in the vestibular-lingual direction, while the G3 featured larger conicity values ​in the mesial-distal direction. The data of this research corroborate with the results found in the literature, as the values ​are higher than those recommended in the literature and through the questionnaire, it was observed that there was theoretical knowledge assimilation regarding teeth preparation, favoring the decision-making in relation to teaching methods adequacy for the discipline of Fixed Prosthodontics in this Higher Education institution (AU).

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Las preparaciones dentales para prótesis fija, involucran al tejido duro, además la proximidad que existe con la encía hace necesario la comprensión de su estructura y la función del aparato de protección, para que las restauracionesno invadan el ancho biológico constituido por el epitelio de unión y las fibras gingivales; basándonos en los estudios de Gargiulo en 1961, donde la inserción del tejido conjuntivo mide 1.07 mm y la adherencia epitelial 0.97 mm en promedio, sumados al espacio del surco gingival. El biotipo periodontal es de vital importancia para la elección de la altura de terminación del hombro de la preparación, donde el mismo deberá establecerse, previo sondaje óseo a no menos de 2.5 mm de la cresta según Kois (2008). La utilización de materiales y técnicas para la toma de impresiones definitivas deben ser amigables con los tejidos blandos a fin de no producir alteraciones y que las restauraciones sean predecibles, tanto funcional como estéticamente en el transcurso del tiempo

Dental preparations fixed prosthesis, involving the hard tissue, there is also proximity to the gum is necessary to understand the structure and function of the protection device, to restorations without invading the biologic width consisting of the epithelium junction and the gingival fibers; based on Gargiulo studies in 1961, where the insertion of the connective tissue and epithelial measured 1.07 mm 0.97 mm in average adhesion, coupled with sulcular space. The periodontal biotype is of vital importance for the choice of the termination of the shoulder height of the preparation, where it must be established prior tobone sounding no less than 2.5mm crest according Kois (2008). The use of materials and techniques for making final impressions should be friendly soft so as not to alter tissues and restorations predictable, both functionally and aesthetically over time.

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PURPOSE: The goals of part 2 of the study presented here were 1) to assess whether there is a difference in failure mode of different thicknesses (2.0, 1.5, 1.0, and 0.5 mm) of anatomically standardized full contour monolithic lithium disilicate restorations for posterior teeth, and 2) to assess if there is a difference among various crown thicknesses when these restorations are subjected to dynamic load forces common for posterior teeth. MATERIALS AND METHODS: Four groups (n = 10), each with a different thickness of anatomically appropriate all-ceramic crowns, were to be tested as established from the statistical analysis of the preliminary phase. Group 1: 2.0 mm; group 2: 1.5 mm; group 3: 1.0 mm; group 4: 0.5 mm. The specimens were adhesively luted to the corresponding die, and underwent dynamic cyclic loading (380 to 390 N) completely submerged in an aqueous environment until a failure was noted by graphic recording and continuous monitoring. RESULTS: There was a statistically significant difference of the fatigue cycles to failure among four groups (p < 0.001; Kruskal-Wallis test). The mean number of cycles to fail for 2.0 mm specimens was 17 times more than the mean number of cycles to fail for 1.0 mm specimens and 1.5 times more than the mean number of cycles to fail for 1.5 mm specimens. The 0.5 mm specimens failed with one cycle of loading. A qualitative characteristic noted among the 2.0 mm specimens was wear of the area of indenter contact followed by shearing of the material and/or crack propagation. CONCLUSION: Based on the findings of this study, it may be reasonable to consider a crown thickness of 1.5 mm or greater for clinical applications of milled monolithic lithium disilicate crowns for posterior single teeth.

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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.

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Atualmente, o cuidado com a estética vem sendo valorizado de tal forma que, além de ser um referencial de saúde, ter um sorriso bonito significa também estar em harmonia consigo mesmo e ser uma pessoa bem sucedida. Dentro da Odontologia, a procura por um sorriso harmonioso e bonito vem crescendo a cada dia. Essa busca está diretamente relacionada a fatores sociais, culturais e psicológicos, que se alteram em função do tempo, dos valores de vida e da idade do indivíduo. Uma alternativa para a correção de imperfeições nos dentes é a utilização dos laminados cerâmicos que restabelecem a forma, cor, função e harmonia do sorriso, além de proporcionar longevidade do tratamento e satisfação plena do cliente. Os laminados cerâmicos são indicados para a correção de imperfeições dentárias, fraturas e dentições desgastadas pelas forças mastigatórias, substituindo estruturas defeituosas por um esmalte artificial integrado funcional e biologicamente aos tecidos dentários e periodontais. O estudo da resistência à fratura e à fadiga dos laminados cerâmicos fornece dados relativos ao reforço, estabilidade e a manutenção da estrutura dentária, prevenindo o preparo total da coroa dental. O presente relato apresenta, com base na literatura, uma reabilitação estética do sorriso usando laminados cerâmicos sem realização de preparo ou desgaste dos dentes. A comunicação harmônica entre o cirurgião dentista, TPD e os critérios científicos de planejamento são de fundamental importância para a obtenção resultados estéticos e funcionais com longevidade clínica.

Nowadays, the care with aesthetics aspects has been valued in such a way that, besides being an indicator of health, a beautiful smile is also associated to be in harmony with yourself and being a successful person. In Dentistry, the search for a beautiful and harmonious smile is increasing each day. This search is directly related to social, psychological and cultural factors that change with time, as with life values and age of the person. An alternative to correct dental imperfections is the use of laminate veneers that restore the shape, color, function and harmony of the smile, as well as provide longevity to the treatment and the complete satisfaction of the patient. The laminate veneers are indicated for the correction of dental imperfections, fractures and teeth worn by chewing forces, replacing defective structures by artificial enamel functionally and biologically integrated to the dental and periodontal tissues. The study on fracture and fatigue resistance of the laminate veneer provides data on the reinforcement, stability and maintenance of the dental structure, preventing the total preparation of the dental crown. This report is based on the literature and presents an aesthetical rehabilitation of the smile using laminate veneers without the realization of preparation or wear of the teeth. An effective communication between dentist surgeon, dental technician and the scientific criteria of planning are fundamental for obtaining aesthetic and functional results with clinical longevity.

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STATEMENT OF PROBLEM: Teeth restored with posts are more frequently associated with bone loss, but there is no evidence to suggest that the post type and the presence of bone loss influence biomechanical behavior. PURPOSE: The purpose of this study was to evaluate the effect of alveolar bone loss, post type, and ferrule presence on the biomechanical behavior of endodontically treated maxillary canines. MATERIAL AND METHODS: For the experimental analysis, 40 human canine teeth were selected and divided into 8 experimental groups (n=5) according to 3 treatment variations: with or without 5.0 mm of bone loss (bl), with or without a ferrule, and restored with cast post and cores or glass fiber post. The restored canines were loaded at 15 degrees, and deformation was measured with strain gauges placed on the buccal and proximal root surfaces. Strain results were analyzed by 3-way analysis of variance (ANOVA) and the Tukey HSD tests (α=.05). For the finite element analysis, eight 3D models were created by following the same variations of the experimental analysis. The models were analyzed by using the maximum principal stress criteria for stress distribution analysis. RESULTS: The absence of a ferrule significantly increased the buccal and proximal strain values. The post type influenced the stress distribution, mainly at the interface of post and dentin. The bone loss significantly increased the stress concentration and strain values, mainly on root dentin and surrounding cortical bone. CONCLUSIONS: The presence of a ferrule improved the mechanical behavior. The 5.0 mm of bone loss significantly increased the stress concentration and the strain on the root dentin.

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PURPOSE: To evaluate the fracture strength of three different types of tooth preparation design for ceramic veneers and determine whether there is any correlation between the preparation performed and the type of failure observed, by means of a meta-analysis of published in vitro studies. MATERIALS AND METHODS: Three databases were consulted to select the studies, considering previously established inclusion and exclusion criteria. The data extracted were submitted to statistical analysis by means of the software Review Manager 5.1, using the random effect statistical model with a confidence interval of 95%. RESULTS: The results showed a decrease in mean dental fracture strength of 76.53 N in teeth with feathered incisal edge preparations, and 102.82 N for those with palatal chamfers when compared with nonprepared teeth, whereas the preparation with a butt joint showed no significant difference compared to nonprepared teeth (p = 0.37). Ceramic fractures occurred more frequently in the chamfer type than feathered incisal edge design. CONCLUSION: The butt joint is the type of preparation that least affects the strength of the tooth and the chamfer preparation type is more susceptible to ceramic fractures.

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OBJECTIVE: The purpose of this study was to evaluate the fracture strength of roots that were prosthetically restored with cast post and core with or without any remaining coronal structure and with different finish lines. MATERIALS AND METHODS: Sixty bovine incisors were sectioned below the cementoenamel junction, endodontically treated and randomly divided into six experimental groups (n = 10) containing teeth with or without any remaining coronal structure and with a beveled shoulder, a chanfered or a shoulder finish line design. The cast post and core were luted with dual-cured resin cement. The metal crowns were cemented with zinc phosphate cement. The specimens were subjected to a tangential compressive load (135° angle) at a crosshead speed of 0.5 mm/min until failure, using a universal testing machine. The fracture strength data were analyzed using the ANOVA and LSMeans (least square means) tests (α = 0.05). RESULTS: The data indicated that the teeth with 2 mm of remaining coronal structure showed the highest fracture strength values when compared with the teeth without any remaining structure (p < 0.05). As to the different finish line designs, the highest fracture strength values were obtained for the beveled shoulder, followed by the chanfered and then by the shoulder designs (p < 0.05). CONCLUSIONS: It may be concluded that, to increase fracture strength, a beveled shoulder and 2 mm of remaining coronal structure are the ideal conditions.

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The restoration of endodontically treated anterior teeth (ETAT) may pose a significant clinical challenge given the wide variety of therapeutic options available. Accurate analysis of the remaining tooth structure is critical in the diagnostic process, leading to selection of the proper treatment option. A novel, simple, and precise classification that allows the evaluation of ETAT is presented. Important factors related to the crown or abutment such as height, wall thickness, and circumferential integrity and root-related factors such as diameter of the canal, depth of the preparation, and canal shape are discussed. This classification may serve to establish a comprehensive diagnosis and assign prognosis to ETAT, which may be helpful for interclinician communication and standardized comparisons in clinical research.

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STATEMENT OF THE PROBLEM: Full-coverage all-ceramic restorations are widely used. The impact of various classifications of luting agent on marginal discrepancies is not well understood. PURPOSE: The purpose of this study was to evaluate the cervical fit of all ceramic crowns (IPS e.maxPress, Cergogold, and In Ceram) on bovine teeth with two luting agents before and after cementation. MATERIALS AND METHODS: Ninety bovine incisors were embedded in resin. The coronal portions of the teeth were prepared to receive full-coverage crowns. Thirty crowns of 7.0 ± 0.5 mm height, 8.0 mm cervical diameter, and 4.2 mm incisal diameter were fabricated for each ceramic system. The crowns were seated on the teeth, and the marginal discrepancy was measured using a measuring microscope. Then, 15 crowns of each ceramic system were luted on the teeth with resin cement (Variolink II) or resin-modified glass ionomer cement (Rely X luting), and the marginal discrepancy was measured. The results were submitted to analysis of variance, t test and Tukey's test (p<0.05). RESULTS: The three ceramic systems showed cervical fits after cementation statistically inferior to cervical fits before cementation for the two cements. The IPS e.maxPress showed values for cervical fit statistically superior to Cergogold before cementation. No statistically significant difference was found between IPS e.maxPress and In Ceram and In Ceram and Cergogold. After cementation, no statistically significant difference was found for the three ceramics systems when luted with resin or resin-modified glass ionomer luting agents. CONCLUSIONS: Within the limitations of this study, it can be concluded that both cements studied increase the marginal discrepancy between the crown and the preparation for the three ceramic systems evaluated.

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OBJECTIVES: To investigate if general dental practitioners (GDPs) in private practice in Jordan follow universal guidelines for preparation of anterior teeth for resin bonded all-ceramic crowns (RBCs). MATERIAL AND METHODS: A sample (n=100) of laboratory models containing 208 tooth preparations for IPS Empress and In Ceram, featuring work from different GDPs, was obtained from 8 commercial dental laboratories. Aspects of preparations were quantified and compared with accepted criteria defined following a review of the literature and recommendations of the manufactures' guidelines. RESULTS: Subgingival margins on the buccal aspect were noticed in 36 percent of the preparations, 54 percent demonstrated overpreparation with a tendency to overprepare the teeth on the mesiodistal plane more than buccolingual plane. Twenty percent of samples presented a shoulder finish line while a chamfer margin design was noticed in 39 percent. Twenty-nine percent and 12 percent of samples had either a feathered or no clear margin design respectively. Incisal underpreparation was observed in 18 percent of dies of each type. Only 17 percent of all preparations were found to follow the recommended anatomical labial preparations while 29 percent of the RBC preparations were found to have the recommended axial convergence angle. In total, 43 percent of preparations were found to have the recommended depth of the finish line. CONCLUSIONS: It was found that relevant guidelines for RBC preparations were not being fully adhered to in private practice in Jordan.

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OBJECTIVES: To investigate if general dental practitioners (GDPs) in private practice in Jordan follow universal guidelines for preparation of anterior teeth for resin bonded all-ceramic crowns (RBCs). MATERIAL AND METHODS: A sample (n=100) of laboratory models containing 208 tooth preparations for IPS Empress and In Ceram, featuring work from different GDPs, was obtained from 8 commercial dental laboratories. Aspects of preparations were quantified and compared with accepted criteria defined following a review of the literature and recommendations of the manufactures' guidelines. RESULTS: Subgingival margins on the buccal aspect were noticed in 36% of the preparations, 54% demonstrated overpreparation with a tendency to overprepare the teeth on the mesiodistal plane more than buccolingual plane. Twenty percent of samples presented a shoulder finish line while a chamfer margin design was noticed in 39%. Twenty-nine percent and 12% of samples had either a feathered or no clear margin design respectively. Incisal underpreparation was observed in 18% of dies of each type. Only 17% of all preparations were found to follow the recommended anatomical labial preparations while 29% of the RBC preparations were found to have the recommended axial convergence angle. In total, 43% of preparations were found to have the recommended depth of the finish line. CONCLUSIONS: It was found that relevant guidelines for RBC preparations were not being fully adhered to in private practice in Jordan.

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