Marginal Bone Loss Around Early-Loaded SLA and SLActive Implants: Radiological Follow-Up Evaluation Up to 6.5 Years.

PURPOSE: The aim of this study was to compare marginal bone loss around early-loaded SLA and SLActive tissue-level implants (Straumann Dental Implants; Institut Straumann AG, Basel, Switzerland) after a mean of 81-month follow-up period. MATERIAL AND METHODS: One hundred seven SLA and 68 SLActive implants were placed in 55 patients and loaded with final restoration after 8 and 3 weeks of healing time, respectively. Marginal bone loss around implants was determined radiographically at initial and after a mean observation time ranging between 20 and 81 months. The effect of location (mandible vs maxilla), smoking habit, sex, implant length and diameter, and the type of prosthesis on the marginal bone loss was evaluated. RESULTS: The overall cumulative survival rate was 98.2% being 99% for SLA implants and 97% for SLActive implants. After 20-month follow-up period, mean marginal bone loss values for the SLA and SLActive implants were 0.24 and 0.17 mm, respectively. After 81 months, mean marginal bone loss for the SLA and SLActive implants reached 0.71 and 0.53 mm, respectively. Marginal bone loss was affected by the length and type of implant and patients' smoking habit after a mean observation time of 20 months. However, none of the parameters had any significant effect on the marginal bone loss after a follow-up period of 81 months. CONCLUSION: With both SLA and SLActive implants, successful clinical results could be achieved up to 6.5 years of follow-up period.

Multidisciplinary treatment approach in a patient with history of nasopharyngeal carcinoma.

Radiotherapy in NPC patients has side effects on the dentition, which affects quality of life dramatically. This case report presents multidisciplinary dental treatment approach in a 17-year-old male patient with a history of nasopharyngeal carcinoma (NPC), which was treated with chemotherapy and radiotherapy. The adolescent patient applied to dental hospital 4 years after the radiotherapy with aesthetic and functional problems on dentition affecting psychological, social, and physical aspects of his life. The dentition of the patient demonstrated the severe destruction as a devastating side effect of radiotherapy. With a successful multidisciplinary approach, our patient's aesthetics, function, and self-confidence were obtained. Well-established procedures, which include preventative care and maintenance, can reduce the duration and expenses of the treatment and help in challenging the life-long complications of radiotherapy.

Rehabilitation of posterior maxilla with zygomatic and dental implant after tumor resection: a case report.

Zygomatic implants have been used for dental rehabilitation in patients with insufficient bone in the posterior upper jaw, due to, for example, tumor resection, trauma, or atrophy. Zygomatic implants are an alternative to complex free or vascularized bone grafting and distraction osteogenesis. A 42-year-old male patient with a severe defect in the right posterior maxilla, starting from the first canine region, which had occurred after tumor resection 3 years earlier, was referred to our department. One zygomatic implant (Brenemark System, Nobel Biocare, Goteborg, Sweden) to the zygoma and one dental implant to the canine region were placed. After a 5-month osseointegration period, a fixed denture was fabricated and adapted to the implants. Although the surgical and prosthetic procedures for zygoma implants are not easy, the final outcomes can be successful with appropriate planning.

Posterior maxillary segmental osteotomy for restoring the mandible with dental implants: a clinical report.

Posterior segmental collapse causes narrowing of interarch space and prevents adequate restoration in the posterior quadrant. Posterior maxillary segmental osteotomy (PMSO) is an alternative option that enables prosthodontic restoration with an implant-supported fixed partial denture. The following clinical report describes prosthodontic rehabilitation with fixed prostheses after a posterior maxillary segmental osteotomy for a patient with a partially edentulous mandible.

Fractographic analyses of zirconia-based fixed partial dentures.

OBJECTIVES: Advances in ceramic processing techniques enable clinicians and ceramists to fabricate all-ceramic fixed partial dentures (FPDs) for posterior regions using high-strength yttria-stabilized tetragonal zirconia polycrystals (Y-TZP). However, failures occur in ceramic FPDs due to their design. The objectives of this study were to determine the site of crack initiation and the causes of fracture in clinically failed zirconia-based ceramic FPDs. METHODS: Five clinically failed four-unit Y-TZP-based FPDs (Cercon ceramics, DeguDent GmbH, Hanau, Germany) were retrieved and analyzed. The fragments containing the fracture origins in the veneers (Cercon Ceram S Veneering Ceramic, DeguDent GmbH, Hanau, Germany) of two samples were missing but the rest of veneer structures were present. The other three samples had their veneers intact. Fracture surfaces were examined using fractographic techniques, utilizing both optical and scanning electron microscopes (SEM). Quantitative fractography and fracture mechanics principles were used to estimate the stresses at failure. RESULTS: Primary fractures initiated from the gingival surfaces of connectors at veneer surfaces in four out of the five samples. However, critical flaw sizes could be measured in three of the five cases since fracture origins were lost in the remaining two due to local fragmentation at the crack initiation site. Delaminations between glass veneer and zirconia core were observed in Y-TZP-based FPDs and a secondary fracture initiated from the zirconia core. Secondary fracture controlled the ultimate failure. Failure stresses of the fixed partial dentures that failed due to zirconia fracture ranged from 379 to 501 MPa. Fractures that had origins on the glass veneer surface had failure stresses between 31 and 38 MPa. SIGNIFICANCE: Primary fractures in clinically failed Y-TZP-based FPDs initiated from the veneer surfaces. Interfacial delamination in glass veneer/zirconia core bilayer dental ceramic structures controlled the secondary fracture initiation sites and failure stresses in Y-TZP-based fixed partial dentures.

Two-year clinical evaluation of lithia-disilicate-based all-ceramic crowns and fixed partial dentures.

OBJECTIVES: The aim of this study was to evaluate the clinical performance of crowns and fixed partial dentures (FPDs) made with the Empress 2 system over a 2-year period. METHODS: Twenty anterior or posterior all-ceramic (Empress 2) crowns and 20 anterior or posterior, three-unit fixed partial dentures were fabricated for 15 patients. Evaluations of the restorations were performed at baseline and once a year during the 2-year follow-up period. U.S. Public Health Service criteria were used to examine the marginal adaptation, color match, secondary caries and visible fractures in the restorations. Survival rate of the restorations were determined using Kaplan-Meier statistical analysis. RESULTS: U.S. Public Health Service criteria showed 100% Alpha scores concerning recurrent caries for both crowns and FPDs. No crown fractures were observed during the 2-year follow-up, however, 10 (50%) catastrophic failures of FPDs occurred. Five (25%) failures occurred within the 1-year clinical period and the others (25%) within the second year. SIGNIFICANCE: Single unit Empress 2 all-ceramic crowns exhibited a satisfactory clinical performance over 2-year period. Furthermore, the high fracture rate of Empress 2 FPDs limits the usage of Empress 2 for the fabrication of all-ceramic FPD.

Immediately loaded anterior single-tooth implants: two cases.

Immediate loading of implants into fresh extraction sockets has the advantage of decreasing the period of healing, reducing the resorption of the alveolar bone, and achieving optimal esthetic results. These cases reveal the clinical success of immediate loaded single-tooth implants placed in fresh extraction sites.

Influence of occlusal forces on stress distribution in preloaded dental implant screws.

STATEMENT OF PROBLEM: Abutment and prosthetic loosening of single and multiple screw-retained, implant-supported fixed partial dentures is a concern. PURPOSE: The purpose of this study was to investigate stress distribution of preloaded dental implant screws in 3 implant-to-abutment joint systems under simulated occlusal forces. MATERIAL AND METHODS: Three abutment-to-implant joint systems were simulated by using the 3-dimensional finite element analysis method: (1) Branemark external hexagonal screw-retained abutment, (2) ITI 8-degree Morse tapered cemented abutment, and (3) ITI 8-degree Morse tapered plus internal octagonal screw-retained abutment. A thermal load and contact analysis method were used to simulate the preload resulting from the manufacturers' recommended torques in implant screw joint assemblies. The simulated preloaded implants were then loaded with 3 simulated static occlusal loads (10 N; horizontal, 35 N; vertical, 70 N; oblique) on the crown position onto the implant complex. RESULTS: Numeric and graphical results demonstrated that the stresses increased in both the abutment and prosthetic screws in the finite element models after simulated horizontal loading. However, when vertical and oblique static loads were applied, stresses decreased in the external hexagonal and internal octagonal plus 8-degree Morse tapered abutment and prosthetic screws with the exception of the prosthetic screw of ITI abutment after 70-N oblique loading. Stresses increased in the ITI 8-degree Morse tapered cemented abutment after both vertical and oblique loads. CONCLUSION: Although an increase or decrease was demonstrated for the maximum calculated stress values in preloaded screws after occlusal loads, these maximum stress values were well below the yield stress of both abutment and prosthetic screws of 2 implant systems tested. The results imply that the 3 implant-to-abutment joint systems tested may not fail under the simulated occlusal forces.

Effect of thermocycling on tensile bond strength of six silicone-based, resilient denture liners.

STATEMENT OF PROBLEM: Adhesion failure between silicone resilient denture lining materials and denture base resin is commonly encountered in clinical practice. Adhesion failure results in localized unhygienic conditions at the debonded regions and often causes functional failure of the prosthesis. PURPOSE: The purpose of this study was to investigate the effect of thermocycling on the tensile bond strength of 6 soft lining materials. MATERIAL AND METHODS: Six commonly used silicone-based resilient denture liners (Ufigel C, Ufigel P, Mollosil, Molloplast B, Permafix, and Permaflex) were chosen for the investigation. The bond strength was determined, in tension, after processing to PMMA. The resilient denture liners for each group (n = 24) were 10 x 10 x 3 mm and were processed between 2 polymethyl methacrylate specimens according to manufacturer's instructions. Two PMMA specimens were prepared by investing brass dies with a 3-mm-thick spacer in a denture flask. Specimens were made by processing the resilient denture liners against the polymerized PMMA block. After polymerization, the brass spacer was removed from the mold, the 2 PMMA resin specimens were trimmed, and the surfaces to be bonded were smoothed. The PMMA block was placed back into the molds and the resilient denture liners were packed into the space made by brass spacer, trial packed, and polymerized according to the manufacturer's instructions. Half of the specimens for each group were stored in water for 24 hours, and the other half were thermocycled (5000 cycles) between baths of 5 degrees and 55 degrees C. All specimens were placed under tension until failure in a universal testing machine at a crosshead speed of 5 mm/min. The maximum tensile stress before failure and mode of failure were recorded. The mode of failure was characterized as cohesive, adhesive, or mixed mode, depending on whether the fracture surface was in the soft liner only, at the denture base-soft liner interface only, or in both. Failure strength was recorded in kg/cm(2). Results were tested by multiple analysis of variance (ANOVA) for mode of failure (adhesive, cohesive, and mix), 2-way ANOVA (storage-products), and 1-way ANOVA (storage-products interaction, before and after thermocycling). Duncan's test was used to determine whether significant changes in the tensile bond properties of the materials occurred during thermocycling. RESULTS: Varying degrees of bond strengths were found for soft lining materials and were significantly different (P<.05). Results of this study also indicated that the bond strengths of soft lining materials had significantly decreased after thermocycling except Ufigel C and Mollosil. CONCLUSIONS: Because the adequate adhesive value for soft lining materials is given 4.5 kg/cm(2), all of the materials were acceptable for clinical use.