Erhan Dilber

Fabricating Complete Dentures with CAD/CAM and RP Technologies.

Two techological approaches for fabricating dentures; computer-aided design and computer-aided manufacturing (CAD/CAM) and rapid prototyping (RP), are combined with the conventional techniques of impression and jaw relation recording to determine their feasibility and applicability. Maxillary and mandibular edentulous jaw models were produced using silicone molds. After obtaining a gypsum working model, acrylic bases were crafted, and occlusal rims for each model were fabricated with previously determined standard vertical and centric relationships. The maxillary and mandibular relationships were recorded with guides. The occlusal rims were then scanned with a digital scanner. The alignment of the maxillary and mandibular teeth was verified. The teeth in each arch were fabricated in one piece, or set, either by CAM or RP. Conventional waxing and flasking was then performed for both methods. These techniques obviate a practitioners need for technicians during design and provide the patient with an opportunity to participate in esthetic design with the dentist. In addition, CAD/CAM and RP reduce chair time; however, the materials and techniques need further improvements. Both CAD/CAM and RP techniques seem promising for reducing chair time and allowing the patient to participate in esthetics design. Furthermore, the one-set aligned artificial tooth design may increase the acrylics durability.

A review of computer-aided design/computer-aided manufacture techniques for removable denture fabrication

The aim of this review was to investigate usage of computer-aided design/computer-aided manufacture (CAD/CAM) such as milling and rapid prototyping (RP) technologies for removable denture fabrication. An electronic search was conducted in the PubMed/MEDLINE, ScienceDirect, Google Scholar, and Web of Science databases. Databases were searched from 1987 to 2014. The search was performed using a variety of keywords including CAD/CAM, complete/partial dentures, RP, rapid manufacturing, digitally designed, milled, computerized, and machined. The identified developments (in chronological order), techniques, advantages, and disadvantages of CAD/CAM and RP for removable denture fabrication are summarized. Using a variety of keywords and aiming to find the topic, 78 publications were initially searched. For the main topic, the abstract of these 78 articles were scanned, and 52 publications were selected for reading in detail. Full-text of these articles was gained and searched in detail. Totally, 40 articles that discussed the techniques, advantages, and disadvantages of CAD/CAM and RP for removable denture fabrication and the articles were incorporated in this review. Totally, 16 of the papers summarized in the table. Following review of all relevant publications, it can be concluded that current innovations and technological developments of CAD/CAM and RP allow the digitally planning and manufacturing of removable dentures from start to finish. As a result according to the literature review CAD/CAM techniques and supportive maxillomandibular relationship transfer devices are growing fast. In the close future, fabricating removable dentures will become medical informatics instead of needing a technical staff and procedures. However the methods have several limitations for now.

Effect of Different Surface Treatments on Porcelain-Resin Bond Strength.

PURPOSE The aim of this study was to evaluate the effects of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. MATERIALS AND METHODS A total of 192 disk-shaped cores were prepared using two all-ceramic systems, of which 168 were submitted to SBS tests, and 24 were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The ceramics used were IPS Empress e.max (EX) lithium glass-ceramic and Vita In-Ceram Zirconia glass-infiltrated zirconia (ICZ). The specimens were randomly divided into seven groups (n = 12) on the basis of the surface treatment used: control; SB-sandblasting with 50 μm Al2 O3 particles; CJ-chairside silica coating with 30 μm SiO2 particles and silanization (Clearfil Porcelain Bond Activator); HF-etching in 5% hydrofluoric acid and silanization; ER-etching with an Er:YAG laser (10 W); ND-Nd:YAG laser etching (0.8 W); and FS-etching with a femtosecond laser (860 mW). A luting cement (Clearfil Esthetic) was photopolymerized on each treated ceramic disk. After subjecting the specimens to thermocycling (1000 cycles, 5°C to 55°C), SBS tests were performed using a universal testing machine. The data were analyzed with two-way ANOVA and Tukeys tests using a significance limit of 5%. RESULTS Among the EX ceramics, the CJ (29.10 MPa) and HF (26.07 MPa) specimens had statistically higher SBS values. For the ICZ ceramics, the highest value (28.08 MPa) was obtained for the CJ specimens. CONCLUSIONS Silanization after coating with silica improves the bond strengths of both EX and ICZ specimens, while HF etching is favorable only for the EX specimens.

Comparison of fracture resistance between cast, CAD/CAM milling, and direct metal laser sintering metal post systems

PURPOSE The purpose of this study was to compare the fracture resistance of Co-Cr post-cores fabricated with 3 different techniques: traditional casting (TC), computer-aided design and manufacturing (CAD/CAM) milling (CCM) and direct metal laser sintering (DMLS). METHODS Forty intact human mandibular premolar were endodontically treated. The roots were then randomly divided into four groups according to the post systems: the control group was only filled with gutta percha. Co-Cr metal posts were fabricated with TC, CCM and DMLS in the other three groups. The posts were luted with a resin cement and subjected to compression test at a crosshead speed of 1mm/min. The statistical analysis of the data was performed using one-way analysis of variance (ANOVA) and multiple comparison post hoc Tukey tests (α=.05). The samples were examined under a stereomicroscope with ×20 magnification for the evaluation of the fracture types. RESULTS The mean fracture loads were 432.69 N for control, 608.89 N for TC, 689.40 N for DMLS and 959.26 N for CCM. One-way ANOVA revealed significant difference between the groups (p<0.01). In the post hoc Tukey test, there were significant differences between groups except DMLS and TC. CONCLUSION While Co-Cr posts fabricated by TC and DMLS systems performed similarly in terms of fracture resistance, posts fabricated by CCM techniques showed higher fracture resistance values. SIGNIFICANCE Co-Cr metal posts fabricated by CCM and DMLS could be an alternative to TC processing in daily clinical application.

Effects of Different Demineralization-Inhibiting Methods on the Shear Bond Strength of Glass-Ceramics

PURPOSE This in vitro study was undertaken to evaluate the effects of different demineralization-inhibiting methods on the shear bond strength (SBS) of glass-ceramics. MATERIALS AND METHODS Ninety extracted intact human mandibular lateral insicors were randomly divided into six equal groups. Group C was left untreated, while enamel subsurface demineralization was induced in the other groups. In group D, porcelain discs (3 mm in diameter) were cemented to demineralized enamel by using total-etch photopolymerizing luting composite resin without pretreatment. Demineralized specimens in groups F, CA, M, and I were pretreated with fluoride gel, CPP-ACP paste, microabrasion, and resin infiltration, respectively, and then porcelain discs were cemented. SBS (MPa) was calculated from the failure load (N) per bonded area (mm(2)). Fracture types were examined by optical microscopy (40× magnification). Data were analyzed with ANOVA, Tukeys test, and G-test. RESULTS ANOVA revealed significant intergroup differences (p < 0.01). No significant differences in SBS (MPa) were found between groups C (19.48 ± 2.0) and I (20.02 ± 1.6). Lower SBS values were recorded in groups D (7.93 ± 0.8), F (12.51 ± 1.5), CA (17.08 ± 1.3), and M (14.84 ± 1.4). Mixed and cohesive failures were the most prevalent in groups M and I, respectively. CONCLUSION Resin infiltration enhanced the SBS of porcelain discs bonded to demineralized enamel when compared with the other demineralization-inhibiting methods. CLINICAL RELEVANCE Resin infiltration could be useful to enhance adhesion of glass-ceramics to teeth with white spot lesions.

Craniofacial implant-retained auricular prosthesis: a case report.

Implants provide patients with a safe and reliable method for anchoring auricular prostheses that enable restoration of their normal appearance and offer improved quality of life. In this case report, an auricular prosthesis was fabricated for a patient who had lost his right external ear in a traffic accident. Extraoral implants and bar-and-clip retention for the proper connection of the auricular prosthesis to the implant were used.

Adhesion of metal brackets to glassy matrix and hybrid CAD/CAM materials after different physico-chemical surface conditioning

Abstract This study compared the adhesion of metal brackets bonded to different CAD/CAM materials after various surface conditioning methods. CAD/CAM blocks (N = 204, n = 17 per group) of (a) VITA Mark II (VM), (b) IPS e.max CAD (IP), (c) Lava Ultimate (LU), and (d) VITA ENAMIC (VE) were conditioned with one of the following methods: C-Control: (fine diamond bur); CJ: (fine diamond bur + air-abrasion with 30 μm SiO2 + silane), and HF: (fine diamond bur +9.5% hydrofluoric acid + silane). Metal brackets were bonded to the conditioned surfaces of the specimens, stored in artificial saliva for 24 h at 37 °C and thermocycled (×1000). Subsequently, the brackets were debonded under shear in a Universal Testing Machine (1 mm/min). Failure types were analyzed under scanning electron microscope. Data were analyzed using two-way ANOVA and Tukey’s tests (α = 0.05). Two-parameter Weibull distribution values, including the Weibull modulus, scale, and shape, were calculated. Mean bond strength (MPa) values were significantly affected by the surface conditioning method (p < 0.001) but not the CAD/CAM material type (p = 0.052). Bond strengths for all CJ and HF-conditioned specimens were twofold higher (11.83 ± 1.95 − 9.44 ± 1.63) than those for control specimens with all materials (4.73 ± 0.93 − 6.02 ± 0.69). Lower mean values were obtained in LU-CJ (9.78 ± 1.61) and LU-HF (9.44 ± 1.63) than those for other groups (11.83 ± 1.95 − 10.93 ± 1.33) groups (p < 0.05). Weibull distribution showed higher shape values for VM-CJ (11.26) and VM-HF (8.87) than those for other groups (0.82–1.83). In control groups, exclusively adhesive and after conditioning mainly mixed failures were observed. Chairside silica coating or HF conditioning significantly improved metal bracket adhesion to both glassy matrix and hybrid CAD/CAM materials tested, with the most reliable adhesion being observed for feldspathic ceramic.

Custom Cast Post Treatment on an Implant Platform in 2 Patients

T he use of implant-supported prostheses to replace missing natural teeth has become an accepted treatment approach in dentistry. Although implant prostheses have a high overall success rate, numerous complications have been reported, and the device sometimes fails. The biological complications associated with the use of the device include peri-implant radiolucency, peri-implantitis, and loss of osseointegration radiographically. Mechanical failure of implant components can manifest in the form of loosened screws, loss of retention, screw or fixture fracture, and porcelain or framework fracture. Screw complications are caused by screw-joint instability, which may occur due to bruxism, unfavorable superstructure, overloading, malfunction, interceptive occlusal contact, metal fatigue after screw loosening, and component misfit. While several factors may affect screw complications, the most important are (1) adequate preload, (2) a precise fit of the mating implant components, and (3) basic antirotational characteristics of the implant and abutment interface. To avoid screw loosening, a precise fit between the mating implant components is very important; once a screw is loosened, the resulting metal fatigue may lead to screw fracture. The most catastrophic mechanical complication is fixture fracture, which is usually caused by loss of the implant. The causes of fixture fractures in the posterior region include cantilevers, bruxism, and heavy occlusal forces; all lead to bending overload. To avoid fixture fracture, the manufacturer currently recommends the use of a wider diameter fixture and a third fixture, and offsetting the fixtures to achieve a tripod effect. When an abutment screw is fractured or deformed, it must be removed without damaging the implant body for the new abutment. Location of the fracture along the abutment screw dictates the removal method of the broken fragments. If a fracture occurs above the implant head, an explorer, hemostat forceps, or straight probe may be successful in removing the fractured fragments. When the fracture occurs below the implant head, other specialized removal systems are required, such as retrieval instruments (Nobel Biocare, Zurich, Switzerland), the Neo Screw Remover Kit (Neobiotech, Seoul, Korea), and the Implant Repair Kit (ITI Dental Implant System. Institute Straumann, AG, Waldenburg, Switzerland). Removal and replacement of the fractured fragment with a new abutment is the appropriate option for most patients, but in some patients, an alternative solution may be required. The present clinical report presents an alternative method for removal of a deformed abutment screw and trapped healing cup without damaging the implant components.

Comparison of the effect of three different post systems on root fracture

Aim: The aim of this in vitro study was to compare the effect of three different post systems cemented with different systems on root fracture. Materials and Methods: Seventy-five extracted human maxillary canines with single and straight roots were used in this study. After the crowns were removed, root canals were prepared with Reciproc R50 files. Smear layer of roots were removed using 17% Ethylenediaminetetraacetic acid (EDTA) followed by 5.25% NaOCl and distilled water. All the root canals were filled with cold lateral compaction technique using AH Plus root canal sealer and gutta-percha. Samples were stored at 37°C and 100% humidity for 1 week and then post space was prepared using fiber post drills. The roots were then randomly divided into five groups according to the luting cements and post systems: negative control, positive control, glass fiber post [Unicore® (Ultradent, Salt Lake City UT, USA)] + composite core [Grandio SO (Voco GmbH, Cuxhave, Germany)], glass fiber post [Unicore® ] + Rebilda® post-core system, individual cast post core. A load was applied on the crowns of all teeth at 135° to their long axis until fracture occurred. Data were analyzed using one-way analysis of variance (ANOVA) and post-hoc Tukey tests. Results: There was statistically significant difference between the groups. According to the post-hoc Tukey test, cast post core (1949.35 + 316 N) showed statistically significantly higher fracture resistance than all the groups except Unicore® + Rebilda® post-core systems (1722.48 + 144.0 N). Conclusion: Fiber post core system which is an alternative to cast post core systems increased the fracture resistance of the canines with root canal treatment. While irrepairable catastrophic fractures might be seen in cast post-core systems, separations between composite resin core, and root interfaces might be seen in teeth restored with fiber post-core systems.