Abstract Purpose The translucency of CAD/CAM blocks influences the polymerization efficiency of resin cement used underneath. The aim of this study is to evaluate the influence of the translucency parameters (TPs) of current monolithic CAD/CAM blocks on the microhardness of light‐cured or dual‐cured resin cement. Materials and Methods 100 specimens were prepared from five types of CAD/CAM blocks (Mark II, Suprinity, Enamic, e.max, Ultimate), and their TP values were measured by spectrophotometry; 100 resin cement specimens (Duolink) were cured underneath five ceramic specimen groups by indirect LED light for 40 seconds with dual‐cure (with catalyst) and light‐cure (without catalyst) polymerization modes. Control group resin cement specimens (n = 20) were cured with both polymerization modes by direct LED light without any ceramic disc, making 120 resin cement specimens in total. The specimens were then stored in a dry environment for 24 hours before measurement of the polymerization depth with a digital micrometer. Vickers hardness measurements were performed at different resin cement sections. The results were statistically analyzed with 1‐, 2‐, and 3‐way ANOVA, Student's t ‐test and Tukey's HSD test (α = 0.05). Results The highest TP values occurred for Suprinity and Ultimate, whereas the lowest TP value occurred for Enamic ( p < 0.01). The depth of cure and Vickers hardness values changed proportionally with TP value. In all specimens, dual polymerization provided higher depth of cure and Vickers hardness values than those obtained using light polymerization ( p < 0.01). In all specimens except Enamic, the hardness value differences between the sections were statistically insignificant ( p > 0.05). In Enamic, the hardness values for both polymerization types decreased significantly in the deeper sections ( p < 0.01). Conclusions Lower depth of cure was observed as the amount of transmitted light decreased in the investigated materials. In clinical practice, light‐cured resin cements may result in inadequate polymerization for ceramic materials with lower TP values. Zirconia‐reinforced lithium silicate and nanoceramic resins may be reliable restorative materials for a restoration with both optimal esthetics and sufficient mechanical strength resulting from proper polymerization.
This study aimed to investigate the effects of the different dental implant neck designs, diameters, and inclinations, on the stress distributions at the mandibular crestal bone and implant-abutment complex, using three-dimensional (3D) finite element stress analysis (FEA) method. Finite element models of three-unit fixed partial dentures supported with two same length implants (10 mm), placed on the second premolar and second molar regions, were designed. Eight different models were designed according to the implants' neck designs (platform switching/traditional), diameters (4.1 mm/4.8 mm) and the tilting angles of the posterior implants (0°/15°). The anterior implants' widths were 4.1 mm and the neck design of the anterior implants matched the posterior implants. Two types of 100-N loads in vertical and 30° oblique directions were applied separately onto each central fossae and functional cusps of the fixed partial dentures crowns. Algor Fempro Software was used for the simulation and evaluation of the stress levels at the implant-abutment complex and the crestal bone. Stress levels measured at the crestal bone were found to be lower for the platform switching models. However, the platform switching design generated higher stress magnitudes within the implant-abutment complex. Inclined placement of posterior implants increased the amount of stress at the crestal bone around both implants. Biomechanically, selection of the largest diameter possible when using tilted platform switched implants may be recommended at the posterior mandible.
To evaluate the influence of anterior monolithic zirconia and lithium disilicate thickness on polymerization efficiency of dual-cure resin cements.Twelve ceramic disks (4.0-mm diameter) with thicknesses of 0.5, 1, 1.5, 2, 2.5, and 3 mm were prepared from monolithic zirconia (Prettau® Anterior; n = 6) and lithium disilicate (IPS e.max® CAD HT; n = 6). Three dual-cure resin cements (Panavia F 2.0, DuoLink Universal™, and RelyX™ U200) were used for polymerization beneath ceramic disks. For each resin cement, 10 specimens were prepared by light curing under monolithic zirconia and lithium disilicate disks of each thickness. Vickers hardness measurements were conducted at four different measurement depths. Data were statistically analyzed using univariate four-, three-, two-, and one-way analysis of variance and independent samples t-tests.Microhardness of resin cements decreased significantly with increasing measurement depth and thickness of monolithic zirconia or lithium disilicate (P < .001). Cements polymerized under lithium disilicate showed higher microhardness values than did those polymerized under zirconia (P < .001). For both ceramics, Panavia F 2.0 exhibited the greatest microhardness, followed by DouLink Universal and RelyX™ U200 (P < .001).Different dual-cure resin cements may have different polymerization efficiencies, and the type and thickness of the overlying ceramic can influence polymerization.The findings of this study suggest that an increase in the thickness of monolithic lithium disilicate or anterior monolithic zirconia restorations can significantly decrease the microhardness of the dual-cure resin cement polymerized beneath the restoration. Dual-cure resin cements can be used for the cementation of anterior monolithic zirconia restorations up to 2 mm thickness and for monolithic lithium disilicate restorations up to 2.5 mm thickness. However, for lithium disilicate restorations with a ≥2.5 mm thickness and zirconia restorations with a ≥2-mm thickness, different cementation approaches must be further studied, such as: extended light curing; the use of dual-cure resin cement with a higher self-curing component than the ones used in this study; or a self-cure resin cement.
OZET Dis hekimliginde estetik beklentinin artmasi, metal icermeyen dis rengindeki restorasyonlarla ilgili arastirmalarin artmasina sebep olmustur. Seramik materyallerinde son 10 yilda yasanan gelismeler tam seramik uygulamalarinin yayginlasmasina yol acmistir. Tam seramiklerin en onemli dezavantaji kirilmaya karsi yatkinliklaridir. Literaturler seramik materyalindeki kirilmanin, restorasyonun basarisizligina neden olan rapor edilmis komplikasyonlar arasinda en sik rastlanilan komplikasyon oldugunu gostermektedir. Bir tam seramik restorasyonun dayanikliligi, dayanak materyalin ozelliklerine oldugu kadar, kullanilan seramik materyaline, alt yapi-ust yapi baglantisina, kuronun kalinligina, restorasyonun dizaynina ve yapistirma teknigine de baglidir. Tam seramik restorasyonlarin basariyla uygulanabilmesi klinisyenin endikasyona uygun materyal secimi ayrica dogru uretim ve yapistirma teknigi kullanmasiyla mumkun olabilmektedir. Bu calismanin amaci; tam seramik sistemlerle ilgili son yillarda yapilmis arastirmalara dayanarak restorasyonlarin dayanikliligini arttirmaya yonelik onerilerde bulunmak ve klinisyenlere dogru simantasyon teknigini belirlemede rehber olusturmaktir. Tam seramik sistemlerle tedavi basarisini arttirmak icin daha fazla sayida klinik arastirma sonuclarina ihtiyac duyulmaktadir. Anahtar Kelimeler: Tam seramik, dayaniklilik, zirkonya, baglanti, simantasyon SUMMARY The increasing demand for esthetics combined with health has stimulated dental research in metal-free tooth-colored restorations. Developments in ceramic materials have allowed more widespread application of all-ceramic restorations over the past 10 years. The most important disadvantage of all-ceramics is the susceptibility to fracture. The literature shows that fracture of the ceramic material is the most frequently reported complication resulting in failure. The strength of an all-ceramic restoration depends on the characteristics of the supporting material, ceramic material used, core-veneer bond strength, crown thickness, design of the restoration and also cementation techniques. Succesful application of all-ceramic restorations is possible with the clinician's appropriate material choice as well as accurate manufacturing and cementation techniques. The aim of this study was to make suggestions in order to improve the strength of restorations and to guide the clinicians to determine the accurate cementation technique based on recently published all-ceramic based literature. Additional clinical research results are required to improve the treatment success with all-ceramic systems. Key Words: All-ceramic, strength, zirconia, bonding, cementation
OZET Zirkonya, essiz faz degisimi ozelligine bagli olarak kazandigi mekanik ozellikleri sayesinde CAD/CAM tekniklerinin de gelismesiyle birlikte son senelerde dis hekimligi protetik restorasyonlarinda kullanimi oldukca yayginlasmistir. Bu derleme piyasadaki zirkonya materyallerini ozellikleriyle birlikte mikroyapilarina gore siniflandirmistir. Zirkoyanin islenmesi sirasinda kullanilan kazima yontemleri ise mikroyapiyi ve mekanik ozellikleriyle birlikte uzun donem basarisini etkilemektedir. Anahtar Kelimeler: Zirkonya, tam seramik, dayaniklilik, yTZP, CAD/CAM ABSTRACT Zirconia; with several advantages over other ceramic materials, due to the transformation toughening mechanisms, has been recently introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures, in combination with CAD/CAM techniques. This review encompasses the specific types of zirconia available in dentistry, together with their properties. The two main processing techniques, soft and hard machining, are assessed in the light of their possible clinical implications and consequences on the long-term performance of zirconia. Key Words: Zirconia, all-ceramic, strength, zirconia, yTZP, CAD/CAM
Dis hekimliginde estetik beklentinin artmasi, metal icermeyen dis rengindeki restorasyonlarla ilgili arastirmalarin artmasina sebep olmustur. Seramik materyallerinde son 10 yilda yasanan gelismeler tam seramik uygulamalarinin yayginlasmasina yol acmistir. Tam seramiklerin en onemli dezavantaji kirilmaya karsi yatkinliklaridir. Literaturler seramik materyalindeki kirilmanin, restorasyonun basarisizligina neden olan rapor edilmis komplikasyonlar arasinda en sik rastlanilan komplikasyon oldugunu gostermektedir. Bir tam seramik restorasyonun dayanikliligi, dayanak materyalin ozelliklerine oldugu kadar, kullanilan seramik materyaline, alt yapi-ust yapi baglantisina, kuronun kalinligina, restorasyonun dizaynina ve yapistirma teknigine de baglidir. Tam seramik restorasyonlarin basariyla uygulanabilmesi klinisyenin endikasyona uygun materyal secimi ayrica dogru uretim ve yapistirma teknigi kullanmasiyla mumkun olabilmektedir. Bu calismanin amaci; tam seramik sistemlerle ilgili son yillarda yapilmis arastirmalara dayanarak restorasyonlarin dayanikliligini arttirmaya yonelik onerilerde bulunmak ve klinisyenlere dogru simantasyon teknigini belirlemede rehber olusturmaktir. Tam seramik sistemlerle tedavi basarisini arttirmak icin daha fazla sayida klinik arastirma sonuclarina ihtiyac duyulmaktadir.
With the introduction of dental implants to the market, varying restorative options have been successfully added for restoring the function and esthetics of both completely and partially edentulous patients. Accurate prosthodontic rehabilitation is the key factor for providing the long-term success and the survival of osseointegrated implants. Implant-supported restorations can be fabricated with different techniques. The prefabricated abutments provided by the implant companies are accepted as the gold standard because of their biocompatibility and advanced mechanical properties. However, especially for the anterior restorations, they are increasingly being replaced by custom abutments ideally prepared with CAD/CAM techniques; due to disadvantages of prefabricated abutments such as esthetic flaws, mechanical insufficiency resulting from implant placement, unacceptable emergence profile, and unhygienic regions formed under angled abutments. Currently, custom abutments are reported to have functional and esthetic advantages over prefabricated abutments. In this chapter, indications for proper abutment selection, contemporary production techniques, and different abutment materials will be stated, and the current research on the subject will be discussed.
Purpose . The aim of the present study was to investigate the effects of the type and thickness of the zirconia material on the microhardness of the underlying dual-cure resin cement. Materials and Methods . Eight disk-shaped zirconia specimens with a 4-mm diameter and four varying thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were fabricated from two different monolithic zirconia materials: posterior monolithic zirconia (Prettau) and anterior monolithic zirconia (Prettau Anterior). Dual-cure resin cement specimens with a 4-mm diameter and 5-mm height were prepared using Teflon cylinder molds and activated by light beneath the eight zirconia disks and without any zirconia disk for 20 s (n=12). A total of 108 specimens were embedded in acrylic. Vickers hardness of each specimen was measured at three different depths using a microhardness device with a 50-g load. All data were statistically evaluated using three-way ANOVA, one-way ANOVA, independent samples t-tests, and Bonferroni corrected post hoc tests ( α =.05). Results . Dual-cure resin cement’s microhardness was significantly higher for the samples polymerized beneath anterior monolithic zirconia compared to posterior monolithic zirconia. The hardness decreased as the thickness increased for both types of zirconia; the latter was attributed to an attenuated curing efficiency. Conclusion . Microhardness of the dual-cure resin cement is influenced by both the type and the thickness of the monolithic zirconia restoration. Polymerization efficiency for resin cement cured under anterior monolithic zirconia may be superior to cured beneath posterior monolithic zirconia.
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