Group 2 ITI Consensus Report: Prosthodontics and implant dentistry.

OBJECTIVES: Working Group 2 was convened to address topics relevant to prosthodontics and dental implants. Systematic reviews were developed according to focused questions addressing (a) the number of implants required to support fixed full-arch restorations, (b) the influence of intentionally tilted implants compared to axial positioned implants when supporting fixed dental prostheses (FDPs), (c) implant placement and loading protocols, (d) zirconia dental implants, (e) zirconia and metal ceramic implant supported single crowns and (f) zirconia and metal ceramic implant supported FDPs. MATERIALS AND METHODS: Group 2 considered and discussed information gathered in six systematic reviews. Group participants discussed statements developed by the authors and developed consensus. The group developed and found consensus for clinical recommendations based on both the statements and the experience of the group. The consensus statements and clinical recommendations were presented to the plenary (gathering of all conference attendees) and discussed. Final versions were developed after consensus was reached. RESULTS: A total of 27 consensus statements were developed from the systematic reviews. Additionally, the group developed 24 clinical recommendations based on the combined expertise of the participants and the developed consensus statements. CONCLUSIONS: The literature supports the use of various implant numbers to support full-arch fixed prostheses. The use of intentionally tilted dental implants is indicated when appropriate conditions exist. Implant placement and loading protocols should be considered together when planning and treating patients. One-piece zirconia dental implants can be recommended when appropriate clinical conditions exist although two-piece zirconia implants should be used with caution as a result of insufficient data. Clinical performance of zirconia and metal ceramic single implant supported crowns is similar and each demonstrates significant, though different, complications. Zirconia ceramic FDPs are less reliable than metal ceramic. Implant supported monolithic zirconia prostheses may be a future option with more supporting evidence.

Effect of chemical surface treatment of titanium on its bond with dental ceramics.

STATEMENT OF PROBLEM: Airborne-particle abrasion of titanium is a clinically accepted method of surface preparation. As a side effect of airborne-particle abrasion, particles of the abrasive material get embedded into the surface. How particle presence or removal from the titanium surface affects the strength of the titanium-ceramic bond is unclear. PURPOSE: The purpose of this in vitro study was to determine the effect of removing Al2O3 particles embedded into the surface by means of chemical surface treatment on the strength of the titanium-ceramic bond. MATERIAL AND METHODS: Titanium (TritanCpTi 1, Dentaurum, 99.5% Ti) disks were airborne-particle abraded with 110 µm Al2O3 at a pressure of 0.4 MPa and an angle of approximately 45 degrees. The surface was etched chemically using 1 of 8 reagents, and the veneering ceramic applied and fired. The strength of the metal-ceramic bond was determined using the shear strength test. Further, the effect of thermal fatigue on the bond strength was evaluated. The results were analyzed with 2-way ANOVA and the Tukey honest significant difference (HSD) test (α=.05). Fractographic investigations and microscopic tests were also performed to determine the quality of the titanium-ceramic bond. RESULTS: Effective etching of the titanium surface and removal of Al2O3 particles included a 30% water solution of HNO3 + 3% HF, a mixture of HNO3 + HF + glycerin, a 4% solution of HF in H2O2, and a 4% solution of HF in H2O. A statistically significant difference (of about 50%) in bond strength was found between the groups subjected to chemical etching and the control group (P<.05). Additionally, a statistically significant difference (about 25%) was found after thermocycling (P<.05). CONCLUSIONS: Removing the Al2O3 particles embedded into the titanium surface after airborne-particle abrasion lowers the strength of the titanium-ceramic bond (P<.05). Thermocycling also weakens the strength of the titanium-ceramic bond, regardless of the surface preparation (P<.05).

Influence of repeated firings on marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic restorations fabricated with different techniques.

STATEMENT OF PROBLEM: Ill-fitting restorations can jeopardize dental, periodontal, and systemic health. Repeated ceramic firing may influence the fitting accuracy of restorations, but scientific information regarding this issue is lacking. PURPOSE: The purpose of this in vitro study was to assess and compare the influence of repeated firings on the marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic 3-unit fixed partial dentures (FPDs) manufactured with different framework methods, including casting, fully sintered hard alloy milling (FHAM), presintered soft alloy milling (PSAM), and selective laser sintering (SLS). MATERIAL AND METHODS: A total of 60 Co-Cr metal frameworks for 3-unit FPDs were fabricated with 3 different computer-aided design and computer-aided manufacturing (CAD-CAM) techniques and conventional casting for a typodont model. The discrepancy values for premolar and molar abutments were measured by using the silicone replica technique after fabrication of the framework, second firing, fourth firing, and seventh firing. The replicas were separated into mesiodistal and buccolingual cross-sections, and digital images of the cross-sections were obtained with a stereomicroscope at ×80 magnification. The measurement points were examined to record the discrepancy values (µm) with in-built measuring software. The recorded data were subjected to repeated-measures 4-way ANOVA and the Bonferroni post hoc test (α=.05). RESULTS: For all measurement periods, the marginal, axial, axio-occlusal, and occlusal discrepancy values differed significantly among the manufacturing groups (P<.001). Moreover, the repeated firings had a statistically significant influence on the discrepancy values of PSAM, FHAM, and SLS groups (P<.05). The cast group was not significantly affected by repeated firings (P>.05). The PSAM group revealed the lowest discrepancy values at all measurement periods (P<.05), except after the second firing in the marginal and axial locations. CONCLUSIONS: The PSAM-fabricated restorations demonstrated superior fitting accuracy. All manufacturing groups were influenced by repeated firings, except the cast group. The marginal discrepancy values of all manufacturing groups were within the range of clinical acceptability (<120 µm).

In vitro evaluation of marginal, axial, and occlusal discrepancies in metal ceramic restorations produced with new technologies.

STATEMENT OF PROBLEM: Marginal and axial discrepancies of metal ceramic restorations are key to their long-term success. Little information is available for metal ceramic restorations fabricated with soft metal milling and laser sintering technologies. PURPOSE: The purpose of this in vitro study was to compare the marginal, axial, and occlusal discrepancies in single-unit metal ceramic restorations fabricated with new production techniques with those in a single-unit restoration fabricated using a conventional technique. MATERIAL AND METHODS: After the artificial tooth was prepared, impressions were made, and 40 dies were obtained. Dies were randomly divided into 4 groups (n=10). Cobalt-chromium (Co-Cr) cast (C), hard metal milled (HM), laser sintered (LS), and soft metal milled (SM) copings were fabricated. Marginal, axial, and occlusal discrepancies of these copings were measured using the silicone replica technique before and after the application of veneering ceramic. Data were analyzed with repeated measurements 2-way ANOVAs and Bonferroni post hoc tests (α=.05). RESULTS: Significant differences were found in the increase of marginal discrepancy after the application of veneering ceramic in the LS group (P=.016). However, no significant differences in marginal discrepancy were found whether veneering ceramic was applied to copings before or after in the other groups (P>.05). With regard to marginal and occlusal discrepancies, significant differences were found among the production techniques (P<.001 and P<.05, respectively). No significant differences in axial discrepancies were found among the groups (P>.05). CONCLUSION: This in vitro study showed that metal ceramic restorations produced with HM and newly introduced SM techniques exhibited better marginal adaptations than those produced with the LS or C technique.

[Oral rehabilitation with metalloceramic restorations in patients with non-differentiated systemic connective tissue dysplasia].

False formation of connective tissues have a great influence on structure and function of organs and tissues of the human body. In prosthodontics, the changes in connective tissues greatly occur during clinical stages of preparing metal ceramic dentures. The algorithm of treatment patients with connective tissue dysplasia during metal ceramic dentures was developed and introduced into practical dentistry based on studying the morphology and functionality of dentition and clinical experience.

Effect of metal selection and porcelain firing on the marginal accuracy of titanium-based metal ceramic restorations.

STATEMENT OF PROBLEM: Titanium is the most biocompatible metal used for dental casting; however, there is concern about its marginal accuracy after porcelain application since this aspect has direct influence on marginal fit. PURPOSE: The purpose of this study was to determine the effect that metal selection and the porcelain firing procedure have on the marginal accuracy of metal ceramic prostheses. MATERIAL AND METHODS: Cast CP Ti, milled CP Ti, cast Ti-6Al-7Nb, and cast Ni-Cr copings (n=5) were fired with compatible porcelains (Triceram for titanium-based metals and VITA VMK 95 for Ni-Cr alloy). The Ni-Cr alloy fired with its porcelain served as the control. Photographs of metal copings placed on a master die were made. Marginal discrepancy was determined on the photographs using an image processing program at 8 predetermined locations before airborne-particle abrasion for porcelain application, after firing of the opaque layer, and after firing of the dentin layer. Repeated-measures 2-way ANOVA was used to investigate the effect of metal selection and firing stage, and paired t tests were used to determine the effect of each firing stage within each material group (alpha=.05). RESULTS: ANOVA showed that both metal selection and firing stage significantly influenced the measured marginal discrepancy (P<.001), and there was interaction between the 2 variables (P<.001). Student-Newman-Keuls multiple comparison tests showed that there were significant differences between any 2 metals compared, at each stage of measurement. Paired t tests showed that significant changes in marginal discrepancy occurred with opaque firing on milled CP Ti (P=.017) and cast Ti-6Al-7Nb alloy (P=.003). CONCLUSIONS: Titanium copings fabricated by CAD/CAM demonstrated the least marginal discrepancy among all groups, while the base metal (Ni-Cr) groups exhibited the most discrepancy of all groups tested.

Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques.

BACKGROUND: Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. AIM: The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM) technique using direct and indirect optical scanning. MATERIALS AND METHODS: This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS) crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4); post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. RESULTS AND CONCLUSION: Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

Dental Ceramics for Restoration and Metal Veneering.

A survey of the development of dental ceramics is presented to provide a better understanding of the rationale behind the development and clinical indications of each class of ceramic material. Knowledge of the composition, microstructure, and properties of a material is critical for selecting the right material for specific applications. The key to successful ceramic restorations rests on material selection, manufacturing technique, and restoration design, including the balancing of several factors such as residual stresses, tooth contact conditions, tooth size and shape, elastic modulus of the adhesives and tooth structure, and surface state.

Zirconia-based versus metal-based single crowns veneered with overpressing ceramic for restoration of posterior endodontically treated teeth: 5-year results of a randomized controlled clinical study.

OBJECTIVES: The aim of this 5-year randomized controlled trial was to compare the longevity and clinical behavior of single posterior crowns made with pressable ceramic on zirconia and on metal frameworks, and if failures occur, to delineate the contributing factors. METHODS: 72 patients, who needed the covering of at least a molar and/or premolar, were included in the study. All teeth were endodontically treated, with absence of periapical lesion or active periodontitis. Ninety single crowns were made with zirconia or metal framework and covered with pressable veneering ceramics. Two independent examiners assessed the survival of restorations at 6 months, 1-4 and 5 years after restoration placement including periapical radiographs, intraoral photographs, and USPHS modified criteria. The statistical analyses were performed with the Kaplan-Meier method. RESULTS: One core fracture occurred in Zircad/Zirpress crowns and one metal ceramic crown was lost for root fracture. Chipping fracture of the veneering ceramic was detected in 2 metal-ceramic crowns and in 3 zirconia-based crowns. The Estimate Cumulative Survival (ECS) and the Estimate Cumulative Success (ECSs) with standard deviation (SE) were respectively 97,73±2,19 and 92,64±4,14 for zirconia-based crowns whereas 97,44±2,39 and 91,11±4,27 for porcelain fused to metal crowns. CONCLUSIONS: The present randomized controlled trial shows that the survival of zirconia-based and metal-based single crowns is similar over a follow-up period of 5 years. No significant differences in esthetic, functional and biological outcomes were demonstrated between the two groups. The main failure mode was the chipping fracture of the veneering ceramic in both materials. Study number on ClinicalTrial.gov NCT02758457. CLINICAL SIGNIFICANCE: According to the results of this clinical study, zirconia-based rehabilitations with overpressing veneering technique represent a valid alternative to metal-based for posterior single crown restorations.

Metal-composite copings in the aesthetic restoration of the severely compromised patient.

Aesthetic enhancement of the smile can be as simple as performing tooth whitening or as involved as a full-mouth reconstruction. In instances where porcelain veneers are contraindicated, when subgingival margin placement is required, or when it is necessary to conceal dark substructures or provide occlusal stability, metal-ceramic crowns may be required. This presentation highlights the properties of a metal-composite coping and demonstrates its application in a full mouth reconstruction used by the author to achieve the desired functional and aesthetic outcome.

In Vitro Bioactivity Study of RGD-Coated Titanium Alloy Prothesis for Revision Total Hip Arthroplasty.

Total hip arthroplasty (THA) is a common procedure for the treatment of end-stage hip joint disease, and the demand for revision THA will double by 2026. Ti6Al4V (Titanium, 6% Aluminum, and 4% Vanadium) is a kind of alloy commonly used to make hip prothesis. To promote the osseointegration between the prothesis and host bone is very important for the revision THA. The peptide Arg-Gly-Asp (RGD) could increase cell attachment and has been used in the vascular tissue engineering. In this study, we combined the RGD with Ti6Al4V alloy using the covalent cross-linking method to fabricate the functional Ti6Al4V alloy (FTA). The distribution of RGD oligopeptide on the FTA was even and homogeneous. The FTA scaffolds could promote mouse osteoblasts adhesion and spreading. Furthermore, the result of RT-qPCR indicated that the FTA scaffolds were more beneficial to osteogenesis, which may be due to the improvement of osteoblast adhesion by the RGD oligopeptide coated on FTA. Overall, the FTA scaffolds developed herein pave the road for designing and building more efficient prothesis for osseointegration between the host bone and prothesis in revision THA.

All-ceramic alternatives to conventional metal-ceramic restorations.

In the search for the ultimate esthetic restorative material, many new all-ceramic systems have been introduced to the market. One such system, In-Ceram, is primarily crystalline in nature, whereas all other forms of ceramics used in dentistry consist primarily of a glass matrix with a crystalline phase as a filler. In-Cream can be used to make all-ceramic crowns and fixed partial denture frameworks. Three forms of In-Ceram, based on alumina, spinal (a mixture of alumina and magnesia), or zirconia, make it possible to fabricate frameworks of various translucencies by using different processing techniques. This article discusses clinical indications and contraindications for the use of In-Ceram Alumina and In-Ceram Spinell all-ceramic restorations. Particular attention is given to cement considerations using several clinical examples.

All-ceramic restorations: an overview.

Advantages and disadvantages of metal-ceramic and all-ceramic restorations are reviewed particularly from the aesthetic point of view. All-ceramic restorations offer the best results because they let the light through optimally. In constructing all-ceramic crowns on teeth which have been endodontically treated, the material used to rebuild the pin-abutments must be taken into consideration if the best aesthetic results are to be achieved. Materials which, because of their translucent characteristics, are the most aesthetic alternatives to metal alloy pin-abutments in rebuilding teeth which have been endodontically treated, are then described.

The hybrid crown.

A crown type has been described that offers the advantages of both ceramic veneers and metal crowns. More than 200 single crowns and three three-unit bridges of this type have been inserted with no failures after two years. University-based shear and compressive testing is currently being arranged to affirm perceived clinical strength of this new crown type. Comparison testing also will be performed with comparative values for the hybrid crown, all ceramic (various types), and porcelain-fused-to-metal.

Aesthetic evolution of anterior maxillary crowns: a literature review.

The aesthetics of anterior maxillary restorations and health of the surrounding tissues are primary determinants of the successful outcome of a clinical procedure. Various restorative materials and application techniques have been developed to achieve optimal aesthetics. While early porcelain-fused-to-metal restorations exhibited metal margins, the development of shoulder porcelain margins in the 1980s resulted in a significant aesthetic improvement. Only in the 1990s, however, did all-porcelain restorations finally achieve the strength and complete range of optical characteristics exhibited by the natural dentition.

[A clinical evaluation of the use of dentures with a Simet glass-ceramic coating]. / Klinicheskaia otsenka primeneniia zubnykh protezov s sitallovym pokrytiem "Simet".

Positive follow-up results achieved in patients with metal-glass ceramic dentures coated with Simet permit the authors to recommend glass ceramic Simet for wide clinical introduction. In reconstructive dental prosthetics with metal glass ceramic and cermet materials the dentures should be modelled in the articulator. Preventive examinations are recommended once in half a year.

[The preparation of the maxillodental system before using using metal-ceramic dentures]. / Podgotovka zubocheliustnoi sistemy pered primeneniem metallokeramicheskikh protezov.

Orthodontic treatment using cermet dentures was carried out in 496 patients aged 26 to 60. Therapeutic surgical and orthodontic treatment of the maxillodental system was carried out before denture fixation. Late results in periods from 1 to 5 years were followed up in 396 patients. No complications were observed in 384 (96.9%). Only 12 patients developed complications: porcelain fracture in 4, periodontal inflammations in 5, and a partial relapse of occlusion reduction and distal dislocation of the mandible in 3.

Retentiveness of metal coping luted to teeth of uremic patients undergoing hemodialysis using five different luting cements.

OBJECTIVES: This study aimed to assess the retention of metal copings luted to uremic teeth with five different luting agents. METHODS: A total of 35 sound natural molars was collected from uremic patients and randomly assigned into five groups (n=7). The teeth were prepared for metal copings using diamond tips and water coolant. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III). The copings were luted using Fuji I, glass ionomer (GI); Fuji Plus, resin-modified glass ionomer (RMGI); Panavia F 2.0, resin cement; Rely X Unicem, self-adhesive cement (SA); and Adhesor, zinc phosphate cement (ZPh). All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days, and then thermocycled for 5000 cycles (5°C-55°C). The dislodging force was measured using a universal testing machine at a crosshead speed of 2 mm/min. The mode of failure of the loaded adhesive copings was evaluated. Statistical analyses were performed using one-way analysis of variance and Tukey post hoc test. RESULTS: GI and SA cements had the highest and the lowest mean retentive strength, respectively (580.90±17.3, 406.6±12.7). There was no significant difference between ZPh, SA, and resin cements. These cements were inferior to GI and RMGI cements (p<0.05), which showed statistically similar retentive strengths. CONCLUSIONS: The results of this study support the use of glass ionomer and resin-modified glass ionomer cements for luting of metal copings to uremic teeth with retentive preparations.

Implante transalveolar en sustitución de una corona espiga de pronóstico dudoso* / Transalveolar implant to replace a pin crown of doubtful prognosis

La sustitución de los dientes perdidos en la región estética presenta un complejo desafío debido a la dificultad en la reforma de la apariencia natural y de la anatomía papilar. Se Presenta un caso clínico donde se sustituyó un diente con corona espiga de pronóstico dudoso, por un implante inmediato Avanza. Se trata de una paciente de 24 años de edad atendida en la consulta multidisciplinaria de Implantología de la Clínica Docente de Prótesis de Marianao. Tenía una corona espiga en el incisivo central superior derecho, con cambio de coloración que le afectaba su estética. Además se le caía constantemente y estaba ligeramente inflamada por vestibular, lo cual le producía dolor. Después de una evaluación multidisciplinaria y el consentimiento de la paciente, se procede a la retirada de la corona espiga y exodoncia de la raíz del 11 mediante la técnica de colgajo. Inmediatamente se colocó el implante Avanza y se rehabilitó con una prótesis parcial acrílica removible por razones estéticas. Con este tratamiento, la paciente mantuvo el contorno de los tejidos blandos y la altura ósea de la zona intervenida, necesarios para alcanzar excelentes resultados estéticos(AU)

Replacement of missing teeth from the esthetic region poses a complex challenge to dental specialists due to the difficulties involved in reforming natural appearance and papillary anatomy. A clinical case is presented in which a tooth with a pin crown of doubtful prognosis was replaced with an immediate Avanza implant. A 24-year-old female patient presented at the implantology multidisciplinary service of Marianao Prosthetics University Clinic. The patient had a discoloring pin crown in the upper right central incisor that affected her esthetic appearance. Furthermore, the crown constantly fell out and there was slight vestibular swelling, which caused pain. After multidisciplinary evaluation and having obtained the patients consent, the pin crown was removed and root 11 extracted by flap technique. An Avanza implant was immediately placed and rehabilitated with a removable acrylic partial denture for esthetic reasons. With this treatment, the patient maintained the soft tissue contour and bone(AU)