Journal Article•
A comparison of the marginal fit of In-Ceram, IPS Empress, and Procera crowns.
TL;DR: There were no significant differences among the various stages of the crown fabrication: core fabrication, porcelain veneering, and glazing, but the facial and lingual margins exhibited significantly larger marginal discrepancies than the mesial and distal margins.
Abstract: The in vitro marginal fit of three all-ceramic crown systems (In-Ceram, Procera, and IPS Empress) was compared. All crown systems were significantly different from each other at P = 0.05. In-Ceram exhibited the greatest marginal discrepancy (161 microns), followed by Procera (83 microns), and IPS Empress (63 microns). There were no significant differences among the various stages of the crown fabrication: core fabrication, porcelain veneering, and glazing. The facial and lingual margins exhibited significantly larger marginal discrepancies than the mesial and distal margins.
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TL;DR: An overview of CAD/CAM-technologies and systems available for dentistry today is given, which enable the access to new, almost defect-free, industrially prefabricated and controlled materials and an improvement in precision and planning, as well as an increase in efficiency.
Abstract: As in many other industries, production stages are increasingly becoming automated in dental technology. As the price of dental laboratory work has become a major factor in treatment planning and therapy, automation could enable more competitive production in high-wage areas like Western Europe and the USA. Advances in computer technology now enable cost-effective production of individual pieces. Dental restorations produced with computer assistance have become more common in recent years. Most dental companies have access to CAD/CAM procedures, either in the dental practice, the dental laboratory or in the form of production centres. The many benefits associated with CAD/CAM generated dental restorations include: the access to new, almost defect-free, industrially prefabricated and controlled materials; an increase in quality and reproducibility and also data storage commensurate with a standardised chain of production; an improvement in precision and planning, as well as an increase in efficiency. As a result of continual developments in computer hardware and software, new methods of production and new treatment concepts are to be expected, which will enable an additional reduction in costs. Dentists, who will be confronted with these techniques in the future, require certain basic knowledge if they are to benefit from these new procedures. This article gives an overview of CAD/CAM-technologies and systems available for dentistry today.
720 citations
TL;DR: This systematic review of 5-year survival rates and incidences of complications of all-ceramic fixed dental prostheses (FDPs) and to compare them with those of metal‐ceramic FDPs found them to be similar.
Abstract: Objectives: The objective of this systematic review was to assess the 5-year survival rates and incidences of complications of all-ceramic fixed dental prostheses (FDPs) and to compare them with those of metal‐ceramic FDPs. Methods: An electronic MEDLINE and Dental Global Publication Research System search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on all-ceramic and metal‐ceramic reconstructions with a mean follow-up time of at least 3 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by three reviewers. Failure rates were analyzed using standard and random-effects Poisson regression models to obtain summary estimates of 5-year survival proportions. Results: The search provided 3473 titles for single crowns and FDPs and resulted in 100
661 citations
TL;DR: The use of zirconia frameworks for long-span fixed partial dentures or for implant-supported restorations is currently under evaluation and further in vivo, long-term clinical studies will be needed to provide scientific evidence for drawing solid guidelines as discussed by the authors.
403 citations
Cites background from "A comparison of the marginal fit of..."
...[56] Sulaiman F, Chai J, Jameson LM, Wozniak WT....
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...As to the marginal fit, gaps ranging between 60 and 80 mwere detected, demonstrating a suitable prosthetic precision of fit [56,57] and also from the clinical standpoint marginal integrity was reported to be excellent or acceptable [54,55,58]....
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TL;DR: The fit of conventional and CAD/CAM all-ceramic molar crown-copings covered the same range of gap width confirming the assumed hypothesis.
Abstract: summary: Evaluation of the marginal and internal fit of all-ceramic molar crown-copings hypothesizing that Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) fabrication shows the same accuracy of fit as conventional techniques. A set of six individual crown preparations was duplicated 12 times yielding 72 plaster dies. Slip-cast (In-Ceram Zirconia®), heat-pressing (Empress II®) and CAD/CAM crown-copings (Cerec inLab®, DCS®, Decim® and Procera®) were seated on 12 dies each. Marginal and internal gap width was measured in the SEM at 120× magnification. Marginal gap of slip-cast (25 ± 18 μm) was significantly (P 0·05) from slip-cast (25 ± 18 μm) but were smaller (P 0·05) from any of the others. The internal mid-orobuccal gap width of Procera® (136 ± 68 μm) was larger (P 0·05) from Decim®, Procera® and slip-cast. Internal mesiodistal gap width was similar. The fit of conventional and CAD/CAM all-ceramic molar crown-copings covered the same range of gap width confirming the assumed hypothesis.
344 citations
TL;DR: The results suggest that the accuracy of CAD/CAM generated all-ceramic three-unit fixed partial dentures (FPDs) is satisfactory for clinical use.
Abstract: In this study, the hypothesis was tested that the marginal and internal fit of CAD/CAM fabricated all-ceramic three-unit fixed partial dentures (FPDs) can be as good as in metal-ceramic FPDs. Twenty-four all-ceramic FPDs were fabricated and randomly subdivided into three equally sized groups. Eight frameworks were fabricated using the Digident CAD/CAM system (DIGI), another eight frameworks using the Cerec Inlab system (INLA). Vita Inceram Zirkonia blanks were used for both groups. In a third group frameworks were milled from yttrium-stabilized Zirconium blanks using the Lava system (LAVA). All frameworks were layered with ceramic veneering material. In addition, six three-unit metal-ceramic FPDs served as control group. All FPDs were evaluated using a replica technique with a light body silicone stabilized with a heavy body material. The replica samples were examined under microscope. The medians of marginal gaps were 75 microm for DIGI, 65 microm for LAVA and INLA and 54 microm for the conventional FPDs. Only the DIGI data differed significantly from those of the conventional FPDs. Within the limits of this study, the results suggest that the accuracy of CAD/CAM generated three-unit FPDs is satisfactory for clinical use.
337 citations
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1,023 citations
TL;DR: Changes in the subgingival microflora after the placement of restorations with overhanging margins document a potential mechanism for the initiation of periodontal disease associated with iatrogenic factors.
Abstract: The close association between restorations with overhanging margins and chronic destructive periodontitis has been known for many years. However, the mechanisms by which overhanging restorations will interact in the pathogenesis of periodontal disease are still unknown. Generally it is accepted that overhanging restorations contribute to the promotion of the disease process by virtue of their capacity to retain bacterial plaque. The purpose of the present study was to determine if the placement of subgingival restorations with overhanging margins results in changes in the subgingival microflora. 9 dental students with clean teeth and clinically healthy gingivae (GI less than 0.1) gave their consent to participate in the study. 5 MOD cast gold onlays with 1 mm proximal overhanging margins were placed in mandibular molars for 19-27 weeks. They were replaced in a cross-over design by 5 similar onlays with clinically perfect margins which served as controls. Another 5 onlays were placed in reverse order in the remaining patients. Prior to and every 2-3 weeks after insertion, subgingival microbiological samples were obtained by inserting a fine sterile paper point for 30 sec into the gingival sulcus subjacent to the restoration. The predominant cultivable flora was determined using continuous anaerobic culturing techniques. Following the placement of restorations with overhanging margins, a subgingival flora was detected which closely resembled that of chronic periodontitis. Increased proportions of Gram-negative anaerobic bacteria, black-pigmented Bacteroides and an increased anaerobe: facultative ratio were noted. Following the placement of the restorations with clinically perfect margins, a microflora characteristic for gingival health or initial gingivitis was observed. Black-pigmented Bacteroides were detected in very low proportions (1.6-3.8%). These changes in the subgingival microflora were obvious irrespective of whether the restorations with the overhanging margins were placed in the first period of the experiment or following the cross-over. Clinically, increasing gingival indices were detected at the sites where overhanging margins were placed. Bleeding on gentle probing always preceded the peak level of black-pigmented Bacteroides. Loss of attachment was not detected in any site. Changes in the subgingival microflora after the placement of restorations with overhanging margins document a potential mechanism for the initiation of periodontal disease associated with iatrogenic factors.
380 citations
TL;DR: It is established that a significant quantitative relationship existed between the marginal discrepancy and periodontal tissue inflammation for subgingivally located crown margins.
Abstract: Numerous reports have suggested a relationship between marginal adaptation of dental castings and periodontal tissue health, and this study examined this relationship quantitatively. Forty-two crown restorations in 29 randomly selected patients were selected for this study using three criteria. (1) The crowns were placed at the University of North Carolina School of Dentistry; (2) the crowns were in service for a minimum of 4 years; and (3) the crown margins were within the intracrevicular crevice (subgingival). Replica impressions of the facial margins of specific crowns were made with a vinyl polysiloxane impression material, and poured casts were prepared for scanning electron micrograph evaluation. Marginal discrepancy measurements were identified on each micrograph at 10 equally spaced locations along the margin and averaged for each specimen. Periodontal indices of pocket depths, crevicular fluid volume, and gingival index were accumulated for clinical measurements. Pearson correlation and Bonferroni adjusted probability tests were performed, but no significant correlation was found between marginal discrepancy (0.16 +/- 0.13 mm) and pocket depth (2.4 +/- 0.9 mm). However, a strong correlation (p less than 0.001) existed between marginal discrepancy and gingival index (2 +/- 0.8) and between marginal discrepancies and crevicular fluid volume (49.9 +/- 31.1). These results established that a significant quantitative relationship existed between the marginal discrepancy and periodontal tissue inflammation for subgingivally located crown margins.
364 citations
TL;DR: The purpose of this study was to investigate the rate of type I zinc phosphate cement solubility as it relates to the degree of marginal opening and the effects of convective forces on cement dissolution in a dynamic environment.
Abstract: The purpose of this study was to investigate the rate of type I zinc phosphate cement solubility as it relates to the degree of marginal opening. Standardized test samples were constructed that would simulate clinically relevant marginal gaps of 25, 50, 75, and 150 microns and their subsequent cement lines. The study was divided into two phases. Phase 1 evaluated the effects of simple diffusion on cement solubility in a static environment, whereas phase 2 investigated the effects of convective forces on cement dissolution in a dynamic environment. Both the phase 1 and phase 2 studies demonstrated no significant difference in the rate of cement dissolution for the 25-, 50-, and 75-micron test groups. The 150-micron test groups for both studies, however, demonstrated an increase in the rate of cement dissolution. The results of the phase 1 and phase 2 studies should not be compared because different methodologies were used.
257 citations
TL;DR: This method takes the sintering shrinkage of alumina into consideration and makes it possible to produce individual dental copings in dense-sintered, high-purity alumina, which is a biocompatible implant material.
Abstract: A method of manufacturing an all-ceramic crown composed of a coping of dense-sintered, high-purity alumina with dental porcelain is described. This method takes the sintering shrinkage of alumina into consideration and makes it possible to produce individual dental copings in dense-sintered, high-purity alumina, which is a biocompatible implant material. The alumina used has density, grain size, and flexural strength within the limits of the values required in ISO 6474-1981, 'Implants for surgery, ceramic materials based on alumina'.
254 citations