Shear bond strength between different materials bonded with two resin cements

Background: The aim of this study was to compare the shear bond strength between Ni-Cr alloy specimens bonded to air-abraded Ni-Cr, bur-abraded Ni-Cr, etched ceramic and etched enamel substrates using the resin cements RelyX ARC or Enforce. Materials and methods: Ni-Cr specimens were made and sandblasted with Al2O3 airborne-particles. Disc-shaped patterns were made for each of the four experimental substrates: Ni-Cr treated with Al2O3 airborne-particles, Ni-Cr treated with diamond bur abrasion, etched enamel and etched ceramic. Results: Significant differences in shear bond strength were found between the different materials and luting agents evaluated. The Ni-Cr alloy cylinders bonded to Ni-Cr surfaces sandblasted with 50 lm Al2O3 particles and bonded with Enforce achieved the highest bond strength when compared with other substrates (28.9 MPa, p < 0.05). Bur-abraded metal discs had lowest values, regardless the cement used (2.9 and 6.9 MPa for RelyX and Enforce, respectively). Etched enamel and etched ceramic had similar shear bond strengths within cement groups and performed better when RelyX was used. Conclusions: Bonding Ni-Cr to Ni-Cr and ceramic may result in similar and higher bond strength when compared to Ni-Cr/enamel bonding. For metal/metal bonding, higher shear bond strength was achieved with resin cement Enforce, and for metal/ceramic and metal/enamel bonding, RelyX had higher results.

Thermo and mechanical cycling and veneering method do not influence Y-TZP core/veneer interface bond strength

Objectives: The purpose of this study was to evaluate the influence of thermal and mechanical cycling and veneering technique on the shear bond strength of Y-TZP (yttrium oxide partially stabilized tetragonal zirconia polycrystal) core–veneer interfaces. Materials and methods: Cylindrical Y-TZP specimens were veneered either by layering (n = 20) or by pressing technique (n = 20). A metal ceramic group (CoCr) was used as control (n = 20). Ten specimens for each group were thermal and mechanical cycled and then all samples were subjected to shear bond strength in a universal testing machine with a 0.5 mm/min crosshead speed. Mean shear bond strength (MPa) was analysed with a 2-way analysis of variance and Tukey’s test ( p < 0.05). Failure mode was determined using stereomicroscopy and scanning electron microscopy (SEM). Results: Thermal and mechanical cycling had no influence on the shear bond strength for all groups. The CoCr group presented the highest bond strength value ( p < 0.05) (34.72 7.05 MPa). There was no significant difference between Y-TZP veneered by layering (22.46 2.08 MPa) or pressing (23.58 2.1 MPa) technique. Failure modes were predominantly adhesive for CoCr group, and cohesive within veneer for Y-TZP groups. Conclusions: Thermal and mechanical cycling, as well as the veneering technique does not affect Y-TZP core–veneer bond strength. Clinical significance: Different methods of veneering Y-TZP restorations would not influence the clinical performance of the core/veneer interfaces.

Morse taper implants at different bone levels: a finite element analysis of stress distribution

AIM: To explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). METHODS: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench 10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1.5 mm thickness and the trabecular bone completed the bone block. Four groups were formed: group 11CBL (11 mm implant length on cortical bone level), group 11TBL (11 mm implant length on trabecular bone level), group 13CBL (13mm implant length on cortical bone level) and group 13TBL (13 mm implant length on trabecular bone level). Oblique 200 N loads were applied. Von Mises equivalent stresses in cortical and trabecular bones were evaluated with the same design program. RESULTS: The results were shown qualitatively and quantitatively by standard scales for each type of bone. By the results obtained, it can be suggested that positioning the implant completely in trabecular bone brings harm with respect to the generated stresses. Its implantation in the cortical bone has advantages with respect to better anchoring and locking, reflecting a better dissipation of the stresses along the implant/bone interfaces. In addition, the search for anchoring the implant in its apical region in cortical bone is of great value to improve stabilization and consequently better stress distribution. CONCLUSIONS: The implant position slightly below the bone in relation to the bone crest brings advantages as the best long-term predictability with respect to the expected neck bone loss.

Early loading at 21 days of non-submerged titanium implants with a chemically modified sandblasted and acid-etched surface: 3-year results of a prospective study in the posterior mandible

BACKGROUND: This study evaluates 3-year success rates of titanium screw-type implants with a chemically modified sandblasted and acid-etched surface (mod SLA), which were functionally loaded after 3 weeks of healing. METHODS: A total of 56 implants, inserted in the posterior mandibles of 39 partially edentulous patients, underwent undisturbed healing for 3 weeks. At day 21, the implants were fully loaded with provisional crowns. Definitive metal ceramic restorations were fabricated after 6 months of healing. Clinical measurements regarding soft tissue parameters and radiographs were obtained at different time points up to 36 months after implant placement. The soft tissue and radiographic parameters for the mod SLA implants after 3 years in function were compared to a historic control group of implants with an SLA surface using an early loading protocol after 6 weeks. RESULTS: None of the implants failed to integrate. However, two implants were considered "spinners" at day 21 and were left unloaded for an extended period. Therefore, 96.4% of the inserted implants were loaded according to the protocol tested. All 56 implants, including the "spinners," showed favorable clinical and radiographic findings at the 3-year follow-up examination. All 56 implants were considered successfully integrated, resulting in a 3-year survival and success rate of 100%. Dental implants with a mod SLA surface demonstrated statistically significant differences for probing depths and clinical attachment level values compared to the historic control group, with the mod SLA surface implants having overall lower probing depths and clinical attachment level scores. CONCLUSION: This prospective study using an early loading protocol demonstrates that titanium implants with the mod SLA surface can achieve and maintain successful tissue integration over a period of 3 years.

Early loading after 21 days of healing of nonsubmerged titanium implants with a chemically modified sandblasted and acid-etched surface: two-year results of a prospective two-center study

PURPOSE: The aim of this two-center study was to evaluate screw-type titanium implants with a chemically modified, sandblasted and acid-etched surface when placed in the posterior maxilla or mandible, and loaded 21 days after placement. MATERIAL AND METHODS: All 56 patients met strict inclusion criteria and provided informed consent. Each patient displayed either a single-tooth gap, an extended edentulous space, or a distal extension situation in the posterior mandible or maxilla. Eighty-nine dental implants (SLActive, Institut Straumann AG, Basel, Switzerland) were inserted according to an established nonsubmerged protocol and underwent undisturbed healing for a period of 21 days. Where appropriate, the implants were loaded after 21 days of healing with provisional restorations in full occlusion. Definitive metal ceramic restorations were fabricated and positioned on each implant after 6 months of healing. Clinical measurements regarding soft tissue parameters and radiographs were obtained at different time points up to 24 months after implant placement. RESULTS: Of the 89 inserted implants, two (2.2%) implants failed to integrate and were removed during healing, and two (2.2%) additional implants required a prolonged healing time. A total of 85 (95.6%) implants were therefore loaded without incident after 21 days of healing. No additional implant was lost throughout the study period, whereas one implant was lost to follow-up and therefore left unaccounted for further analysis. The remaining 86 implants all exhibited favorable radiographic and clinical findings. Based on strict success criteria, these implants were considered successfully integrated 2 years after insertion, resulting in a 2-year success rate of 97.7%. CONCLUSION: The results of this prospective two-center study demonstrate that titanium implants with a modified SLA surface can predictably achieve successful tissue integration when loaded in full occlusion 21 days after placement. Integration could be maintained without incident for at least 2 years of follow-up.

Apical surgery of a maxillary molar creating a maxillary sinus window using ultrasonics: a clinical case

AIM: To describe a method of carrying out apical surgery of a maxillary molar using ultrasonics to create a lateral sinus window into the maxillary sinus and an endoscope to enhance visibility during surgery. SUMMARY: A 37-year-old female patient presented with tenderness to percussion of the maxillary second right molar. Root canal treatment had been undertaken, and the tooth restored with a metal-ceramic crown. Radiological examination revealed an apical radiolucency in close proximity to the maxillary sinus. Apical surgery of the molar was performed through the maxillary sinus, using ultrasonics for the osteotomy, creating a window in the lateral wall of the maxillary sinus. During surgery, the lining of the sinus was exposed and elevated without perforation. The root-end was resected using a round tungsten carbide drill, and the root-end cavity was prepared with ultrasonic retrotips. Root-end filling was accomplished with MTA(®) . An endoscope was used to examine the cut root face, the prepared cavity and the root-end filling. No intraoperative or postoperative complications were observed. At the 12-month follow-up, the tooth had no clinical signs or symptoms, and the radiograph demonstrated progressing resolution of the radiolucency. KEY LEARNING POINTS: When conventional root canal retreatment cannot be performed or has failed, apical surgery may be considered, even in maxillary molars with roots in close proximity to the maxillary sinus. Ultrasonic sinus window preparation allows more control and can minimize perforation of the sinus membrane when compared with conventional rotary drilling techniques. The endoscope enhances visibility during endodontic surgery, thus improving the quality of the case.

Five-year results of a randomized controlled clinical trial comparing zirconia and titanium abutments supporting single-implant crowns in canine and posterior regions

OBJECTIVES: To test the survival rates, and the technical and biological complication rates of customized zirconia and titanium abutments 5 years after crown insertion. MATERIAL AND METHODS: Twenty-two patients with 40 single implants in maxillary and mandibular canine and posterior regions were included. The implant sites were randomly assigned to zirconia abutments supporting all-ceramic crowns or titanium abutments supporting metal-ceramic crowns. Clinical examinations were performed at baseline, and at 6, 12, 36 and 60 months of follow-up. The abutments and reconstructions were examined for technical and/or biological complications. Probing pocket depth (PPD), plaque control record (PCR) and Bleeding on Probing (BOP) were assessed at abutments (test) and analogous contralateral teeth (control). Radiographs of the implants revealed the bone level (BL) on mesial (mBL) and distal sides (dBL). Data were statistically analyzed with nonparametric mixed models provided by Brunner and Langer and STATA (P < 0.05). RESULTS: Eighteen patients with 18 zirconia and 10 titanium abutments were available at a mean follow-up of 5.6 years (range 4.5-6.3 years). No abutment fracture or loss of a reconstruction occurred. Hence, the survival rate was 100% for both. Survival of implants supporting zirconia abutments was 88.9% and 90% for implants supporting titanium abutments. Chipping of the veneering ceramic occurred at three metal-ceramic crowns supported by titanium abutments. No significant differences were found at the zirconia and titanium abutments for PPD (meanPPD(ZrO2) 3.3 ± 0.6 mm, mPPD(T) (i) 3.6 ± 1.1 mm), PCR (mPCR(Z) (rO) (2) 0.1 ± 0.3, mPCR(T) (i) 0.3 ± 0.2) and BOP (mBOP(Z) (rO) (2) 0.5 ± 0.3, mBOP(T) (i) 0.6 ± 0.3). Moreover, the BL was similar at implants supporting zirconia and titanium abutments (mBL(Z) (rO) (2) 1.8 ± 0.5, dBL(Z) (rO) (2) 2.0 ± 0.8; mBL(T) (i) 2.0 ± 0.8, dBL(T) (i) 1.9 ± 0.8). CONCLUSIONS: There were no statistically or clinically relevant differences between the 5-year survival rates, and the technical and biological complication rates of zirconia and titanium abutments in posterior regions.

A systematic review of the 5-year survival and complication rates of implant-supported single crowns

OBJECTIVES: The objective of this systematic review was to assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological and technical complications. METHODS: An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on SCs with a mean follow-up time of at least 5 years. Failure and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5-year proportions. RESULTS: Twenty-six studies from an initial yield of 3601 titles were finally selected and data were extracted. In a meta-analysis of these studies, survival of implants supporting SCs was 96.8% [95% confidence interval (CI): 95.9-97.6%] after 5 years. The survival rate of SCs supported by implants was 94.5% (95% CI: 92.5-95.9%) after 5 years of function. The survival rate of metal-ceramic crowns, 95.4% (95% CI: 93.6-96.7%), was significantly (P=0.005) higher than the survival rate, 91.2% (95% CI: 86.8-94.2%), of all-ceramic crowns. Peri-implantitis and soft tissue complications occurred adjacent to 9.7% of the SCs and 6.3% of the implants had bone loss exceeding 2 mm over the 5-year observation period. The cumulative incidence of implant fractures after 5 years was 0.14%. After 5 years, the cumulative incidence of screw or abutment loosening was 12.7% and 0.35% for screw or abutment fracture. For supra-structure-related complications, the cumulative incidence of ceramic or veneer fractures was 4.5%. CONCLUSION: It can be concluded that after an observation period of 5 years, high survival rates for implants and implant-supported SCs can be expected. However, biological and particularly technical complications are frequent.

Clinical performance of wide-body implants with a sandblasted and acid-etched (SLA) surface: results of a 3-year follow-up study in a referral clinic

PURPOSE: The aim of this study was to evaluate the 3-year success rates of wide-body implants with a regular- or wide-neck configuration and a sandblasted, large grit, acid-etched (SLA) surface. MATERIALS AND METHODS: A total of 151 implants were consecutively placed in posterior sites of 116 partially edentulous patients in a referral clinic at the School of Dental Medicine, University of Bern. All implants were restored with cemented crowns or fixed partial dentures after a healing period of 6 to 8 weeks (for implants placed without simultaneous bone augmentation) or 10 to 14 weeks (for implants with simultaneous bone augmentation). All patients were recalled 36 months following implant placement for a clinical and radiographic examination. RESULTS: One implant failed to integrate during healing, and 11 implants were lost to follow-up and considered dropouts. The remaining 139 implants showed favorable clinical and radiographic findings and were considered successfully integrated at the 3-year examination. This resulted in a 3-year success rate of 99.3%. Radiographic evaluation of 134 implants indicated stability of the crestal bone levels: During the study period, the crestal bone level changed less than 0.5 mm for 129 implants. CONCLUSION: Successful tissue integration was achieved with wide-body implants with a regular or a wide-neck configuration and an SLA surface with high predictability. This successful tissue integration was well maintained for up to 3 years of follow-up.

Performance of dental implants after staged sinus floor elevation procedures: 5-year results of a prospective study in partially edentulous patients

OBJECTIVES: The aim of this prospective study was to evaluate the 5-year performance and success rate of titanium screw-type implants with the titanium plasma spray (TPS) or the sand-blasted, large grit, acid-etched (SLA) surface inserted in a two-stage sinus floor elevation (SFE) procedure in the posterior maxilla. MATERIAL AND METHODS: A total of 59 delayed SFEs were performed in 56 patients between January 1997 and December 2001, using a composite graft with autogenous bone chips combined with deproteinized bovine bone mineral (DBBM) or synthetic porous beta-tricalcium phosphate (beta-TCP). After a healing period averaging 7.75 months, 111 dental implants were inserted. After an additional 8-14-week healing period, all implants were functionally loaded with cemented crowns or fixed partial dentures. The patients were recalled at 12 and 60 months for clinical and radiographic examination. RESULTS: One patient developed an acute infection in the right maxillary sinus after SFE and did not undergo implant therapy. Two of the 111 inserted implants had to be removed because of a developing atypical facial pain, and 11 implants were lost to follow-up and were considered drop-outs. The remaining 98 implants showed favorable clinical and radiographic findings at the 5-year examination. The peri-implant soft tissues were stable over time; the mean probing depths and mean attachment levels did not change during the follow-up period. The measurement of the bone crest levels (DIB values) indicated stability as well. Based on strict success criteria, all 98 implants were considered successfully integrated, resulting in a 5-year success rate of 98% (for TPS implants 89%, for SLA implants 100%). CONCLUSION: This prospective study assessing the performance of dental implants inserted after SFE demonstrated that titanium implants can achieve and maintain successful tissue integration with high predictability for at least 5 years of follow-up in carefully selected patients.

Zirconia for teeth and implants

This case series reports on the use of nonsilica-based high-strength full ceramics for different prosthetic indications. Fifty-two consecutive patients received tooth- or implant-supported zirconia reconstructions during a 2-year period. The observation period for reexamination was 12 to 30 months. The most frequent indications were single crowns and short-span fixed partial dentures. A few implant superstructures were screw-retained, whereas all remaining restorations were cemented on natural teeth or zirconia implant abutments. Clinical examination included biologic (probing depths, bleeding on probing) and esthetic (Papilla Index) parameters, as well as technical complications. No implant was lost or caused any problems, but two teeth were lost after horizontal fracture. Overall, the periodontal parameters were favorable. Fractures of frameworks or implant abutments were not observed. Abutment-screw loosening occurred once for one premolar single crown. Furthermore, five implant crowns in the posterior region exhibited chipping of the porcelain veneering material. With regard to esthetics, no reconstructions were considered unacceptable, but three crowns were remade shortly after delivery. In this short-term study, it was observed that biologic, esthetic, and mechanical properties of zirconia were favorable, and the material could be used in various prosthetic indications on teeth or implants.

An Investigation of a Particular Weldment Failure

Two sets of weld-test coupons, supposedly made under identical conditions, were submitted to this institution last year for approval and certification under the A.S.M.E. Welder's Qualification Code. The first set of coupons was unsatisfactory. The second set, made by the same operators one month later, was satisfactory.

Clinical outcome of single porcelain-fused-to-zirconium dioxide crowns: a systematic review

STATEMENT OF PROBLEM The increasing demand by patients for esthetic and metal-free restorations has driven the development of ceramic restorations with good esthetic and mechanical stability. Recent clinical studies have investigated the use of zirconium dioxide as a core material for complete crowns and computer-aided-design/computer-aided-manufacturing fabricated restorations. PURPOSE The aim of this systematic review was to evaluate the clinical survival rates of porcelain-fused-to-zirconia (PFZ) single crowns on anterior and posterior teeth and to compare them with metal ceramic (MC) crowns. MATERIAL AND METHODS A systematic search was conducted with PubMed and manual research to identify literature written in English that refers to in vivo studies published from January 1, 1950 through July 1, 2011. Clinical trials that evaluated PFZ and MC single crowns on natural teeth were selected for further analysis. Titles and/or abstracts of articles identified through the electronic searches were reviewed and evaluated for appropriateness. In addition, a hand search of relevant dental journals was peformed, and reference lists of culled articles were screened to identify publications. RESULTS The search resulted in a total of 488 initial matches. Nineteen studies with a total of 3621 crowns met the inclusion criteria. The survival rates of PFZ crowns (total 300) ranged from 92.7% to 100% for a follow-up time of 24 to 39 months, whereas those of MC crowns (total 3321) ranged from 70% to 100% for a follow-up time of 12 to 298 months. Studies that reported long-term results were found only for the MC crown group. CONCLUSIONS The scientific clinical data available to compare PFZ and MC crowns are limited. The survival rates may well be influenced by the selection and appropriate use of the veneering ceramic, and, therefore, additional prospective long-term clinical trials are necessary to draw reliable conclusions.

Are implants more reliable than severely compromised endodontically treated teeth as abutments for zirconia-based FPDs? : In vitro results of long-term preclinical load simulation

OBJECTIVES The aim was to study the impact of the defect size of endodontically treated incisors compared to dental implants as abutments on the survival of zirconia two-unit anterior cantilever-fixed partial dentures (2U-FPDs) during 10-year simulation. MATERIALS AND METHODS Human maxillary central incisors were endodontically treated and divided into three groups (n = 24): I, access cavities rebuilt with composite core; II, teeth decoronated and restored with composite; and III as II supported by fiber posts. In group IV, implants with individual zirconia abutments were used. Specimens were restored with zirconia 2U-FPDs and exposed to two sequences of thermal cycling and mechanical loading. Statistics: Kaplan-Meier; log-rank tests. RESULTS During TCML in group I two tooth fractures and two debondings with chipping were found. Solely chippings occurred in groups II (2×), IV (2×), and III (1×). No significant different survival was found for the different abutments (p = 0.085) or FPDs (p = 0.526). Load capability differed significantly between groups I (176 N) and III (670 N), and III and IV (324 N) (p < 0.024). CONCLUSION Within the limitations of an in vitro study, it can be concluded that zirconia-framework 2U-FPDs on decoronated teeth with/without post showed comparable in vitro reliability as restorations on implants. The results indicated that restorations on teeth with only access cavity perform worse in survival and linear loading. CLINICAL RELEVANCE Even severe defects do not justify per se a replacement of this particular tooth by a dental implant from load capability point of view.

Theory and practice of crown and bridge prosthesis ...

"History of fixed partial prostheses, by Claude Rowe Baker": p. 1-14.