Esthetic implant solutions in the periodontally compromised anterior region. Expanding the indications for immediate implant placement with the socket rebuilding technique (SRT).

Recent literature has shown that tooth extraction in the esthetic zone is followed by enormous amounts of ridge reduction caused by bone and soft tissue remodeling. The clinical implication of this, among other factors that warrant discussion, is the limitations regarding immediate implant placement in the esthetic zone. On the other hand, staged approaches - even those combined with alveolar ridge preservation techniques and/or alveolar ridge reconstruction - do not always show predictable results, so that esthetic compromises are quite common. Only under optimal conditions do the current literature and common consensus reports support the use of immediate implant placement to preserve the natural esthetic architecture of the former periodontal structures that had surrounded the extracted tooth. Absolutely mandatory, among other factors, are a sufficient bony compartment and an adequate soft tissue volume. The present article outlines a clinical methodology to reestablish the missing prerequisites for the immediate placement of implants, even in periodontally compromised and severely reduced situations, combining different approaches reasonably approved by the literature. Thus, the so-called socket rebuilding technique (SRT) is presented in this article to ensure esthetic results under challenging periodontal conditions.

Five-Year Volumetric Evaluation of Periodontally Compromised Sites Restored by Immediate Implant Restorations.

The aim of the present study was the retrospective evaluation of the distance of the labial hard and soft tissue margins from the implant shoulder in 24 periodontally compromised sites that were restored by immediate implant restorations. Volumetric analysis was performed 5 years postoperatively using cone beam computed tomography with limited field of view. In all cases, a labial radiopaque plate component was apparent 5 years postoperatively coronal to the implant shoulder (3.1 ± 0.6 mm), supporting the soft tissue margin, which was extending above this level (5.2 ± 1.1 mm). In 12 of the sites, preoperative evaluation showed that this plate was missing at the time of implant placement.

Interfacial characterization of ceramic core materials with veneering porcelain for all-ceramic bi-layered restorative systems.

OBJECTIVE: The aim of the study was to characterize the elemental distribution at the interface between all-ceramic core and veneering porcelain materials. MATERIALS AND METHODS: Three groups of all-ceramic cores were selected: A) Glass-ceramics (Cergo, IPS Empress, IPS Empress 2, e-max Press, Finesse); B) Glass-infiltrated ceramics (Celay Alumina, Celay Zirconia) and C) Densely sintered ceramics (Cercon, Procera Alumina, ZirCAD, Noritake Zirconia). The cores were combined with compatible veneering porcelains and three flat square test specimens were produced for each system. The core-veneer interfaces were examined by scanning electron microscopy and energy dispersive x-ray microanalysis. RESULTS: The glass-ceramic systems showed interfacial zones reach in Si and O, with the presence of K, Ca, Al in core and Ca, Ce, Na, Mg or Al in veneer material, depending on the system tested. IPS Empress and IPS Empress 2 demonstrated distinct transitional phases at the core-veneer interface. In the glassinfiltrated systems, intermixing of core (Ce, La) with veneer (Na, Si) elements occurred, whereas an abrupt drop of the core-veneer elemental concentration was documented at the interfaces of all densely sintered ceramics. SIGNIFICANCE: The results of the study provided no evidence of elemental interdiffusion at the core-veneer interfaces in densely sintered ceramics, which implies lack of primary chemical bonding. For the glass-containing systems (glassceramics and glass-infiltrated ceramics) interdiffusion of the glass-phase seems to play a critical role in establishing a primary bonding condition between ceramic core and veneering porcelain.

Comparison of fracture resistance and fracture characterization of bilayered zirconia/fluorapatite and monolithic lithium disilicate all ceramic crowns.

PURPOSE: To compare the fracture resistance between bilayered zirconia/ fluorapatite and monolithic lithium disilicate heat-pressed crowns and characterize the mode of fracture failure. MATERIALS AND METHODS: Thirty crown samples were sequentially fitted on a mandibular right first molar metal replica of an ivory prepared molar tooth. The crown specimens were divided in three groups (A, B, and C; n = 10 for each group). Group A consisted of bilayered zirconia/fluorhapatite pressed-over crowns with standard design crown copings (0.7 mm uniform thickness), Group B of bilayered zirconia/fluorhapatite with anatomical design crown copings, and Group C of lithium disilicate monolithic crowns. The samples were then dynamically loaded under water for 100,000 cycles with a profile of 250 N maximum load at 1,000 N/s rate and 2.0 Hz frequency. Loading was performed with a steel ball (5 mm in diameter) coming into contact with the test crown, loading to maximum, holding for 0.2 s, unloading and lifting off 0.5 mm. The samples were then fractured under static loading, in order to determine the ultimate crown strength. Analysis of the recorded fracture load values was carried out with one-way analysis of variance (ANOVA) followed by Tukey tests. Fractured specimens were examined by stereomicroscopy and scanning electron microscopy. RESULTS: The fracture loads measured were (N, means and standard deviations): Group A: 561.87 (72.63), Group B: 1,014.16 (70.18) and Group C: 1,360.63 (77.95). All mean differences were statistically significant (P < 0.001). Catastrophic fractures occurred in Group C, whereas mainly veneer fractures were observed in Groups A and B. CONCLUSION: In the present study, the heat-pressed monolithic lithium-disilicate crowns showed more fracture resistance than zirconia/fluorapatite pressed-over crowns. Within the bilayered groups, the anatomical zirconia coping design presented increased ceramic fracture resistance.

Evaluation of alternative approaches in designing CAD/CAM frameworks for fixed partial dentures.

BACKGROUND: The need for proper framework support for the veneer porcelain in fixed partial dentures (FPDs) has been well documented. The aim of this study was to compare the variations of the support provided by frameworks designed directly on the computer, or indirectly through scanning a wax pattern. MATERIALS AND METHODS: For each of the six upper anterior FPDs that were involved in the study, prior to milling one framework was designed conventionally in wax and scanned and another one was directly digitally designed. The restorations consisted of full coverage retainers and pontics on natural abutment teeth and implant abutments at random. The produced frameworks were evaluated regarding the incisal support they would provide to the veneer material, as this was revealed by a silicon key representing the outer labial contour of the provisional restoration. The distances between the distal and mesial incisaledges and the corresponding negative incisal contour of the key were measured with a digital caliper. Statistical analysis was performed by linear regression with the design method, abutment type and pontic type as independent parameters (a = 0.05). RESULTS: The values recorded were: means ± SD: 3.3 ± (direct CAD), 2.6 ± mm (indirect CAD) 2.7 ± mm (for retainers on natural teeth) 2.7 (on implant abutments), and 3.3 mm (for pontics). Linear regression analysis showed that the indirect technique provided more intimate incisal support for the ceramic veneer on a statistically significant level and even more so in the pontic areas.

Microbiologic evaluation of compromised periodontal sites before and after immediate intrasocket implant placement.

This study aimed to elucidate the changes in subgingival microflora before the extraction of severely periodontally involved teeth and 1 year after immediate implant placement and provisionalization without flap elevation. Clinical parameters were recorded for 20 maxillary anterior teeth from 10 individuals before and after implant treatment. The clinically observed improvement in the soft tissues was found to be compatible with a less pathogenic flora. Concentrations of periodontopathogens in the periodontal sites were heavily reduced when transformed into peri-implant sites, whereas the relevant counts of the beneficial microorganisms were increased.

Spectrophotometric evaluation of the optical influence of different metal alloys and porcelains in the metal-ceramic complex.

STATEMENT OF THE PROBLEM: Color matching between natural teeth, shade guides, and metal-ceramic restorations is a common clinical problem. Difficulties related to color matching arise from structural differences that exist between metal-ceramic crowns and natural teeth, the limited range of available ceramic shades, inadequate shade guides, different types of metal alloys, and varying compositions of ceramic materials. PURPOSE: The aim of this study was to investigate the influence of various metal alloys and 2 porcelains on the final color of metal-ceramic complex. Material and methods Four commercial alloys for metal-ceramic restorations, a Ni-Cr (Thermobond), a Co-Cr (Wirobond), a Pd-rich noble (Cerapal-2), and a high noble Au-alloy (V-Delta) were combined with 2 porcelains (Vita Omega and Ceramco Silver) in metal-ceramic specimens with a standardized thickness of layers. Five disc-shaped (10 x 1 mm) specimens were prepared for each alloy/porcelain combination. Only opaque and dentin layers were applied (shade A3). The specimens were analyzed with a spectrophotometer, and data were obtained in the CIE Lab color system. The recorded data were analyzed with a 2-way multiple analysis of variance , a pair-wise comparison of group means (Student's t test), and finally, a categorical regression analysis of variance (CATREG) (alpha=.01). RESULTS: The types of alloy substrate and overlying porcelain significantly affected the color (P < .01). Au and Co-Cr alloys were found to be brighter (higher L* values) than the Ni-Cr and the Pd alloys ( P <.01, SE 0.239). Ceramco porcelain was found to be most red (higher a* values) of all tested alloys ( P <.01). Gold and Pd alloys caused a yellow shift to the metal-ceramic color compared to the Ni-Cr and the Co-Cr alloys with both porcelains ( P < .01, SE 0.165). The detected color differences were visually perceptible for some alloy-porcelain combinations. CONCLUSIONS: The final color of metal ceramic specimens was influenced both from the type of alloy substructure and from the type of overlying porcelain.

Evaluation of vertical accuracy of interocclusal records.

PURPOSE: The aim of this study was to evaluate four recording materials (polyether, polyvinyl siloxane, acrylic resin, and wax) for their ability to accurately record, maintain, and reproduce the vertical interocclusal relationship. MATERIALS AND METHODS: A metallic apparatus was used to represent the opposing arches; its epoxy resin duplicate represented the working casts. The vertical discrepancies produced because of the presence of the records were measured both after repositioning them on the metal apparatus and after transferring them onto the casts. Two-way ANOVA was performed. RESULTS: Closure through the interocclusal recording materials produced small vertical discrepancies ranging from 24 to 74 microm. When repositioned on the apparatus, the vertical discrepancies were greater. The lowest discrepancy was displayed by polyvinyl siloxane (101 microm) and polyether (107 microm), and the greatest was displayed by wax (168 microm). When records were transferred onto casts, the discrepancies were approximately 0.5 mm, without significant differences among materials. CONCLUSION: Closure through interocclusal recording materials and removal and repositioning of the records on the apparatus produced small vertical discrepancies with clinically insignificant differences between the materials tested. When records of all materials tested were transferred onto casts, vertical discrepancies of approximately 0.5 mm were found, which is of clinical concern.

Three-dimensional computerized stress analysis of commercially pure titanium and yttrium-partially stabilized zirconia implants.

PURPOSE: The purpose of this study was to use three-dimensional finite element analysis to analyze stress distribution patterns in Re-Implant implants made of commercially pure titanium (cpTi) and yttrium-partially stabilized zirconia (YPSZ). MATERIALS AND METHODS: Two three-dimensional finite element analysis models of a maxillary incisor with Re-Implant implants were made, surrounded by cortical and cancellous bone. A porcelain-fused-to-metal crown for the cpTi implant and a ceramic crown for the YPSZ implant were modeled. Stress levels were calculated according to the von Mises criteria. RESULTS: Higher stresses were observed at the area where the implant entered the bone. Stresses were higher at the facial and lingual surfaces than the proximal ones. In cortical bone and at the junction of cortical and cancellous bone, stress distribution presented a pattern of alternating higher (4.0 to 5.0 MPa) and lower (1.3 to 2.0 MPa) stress areas. Higher stresses were found at the apical third of the implant-to-bone junction as well. CONCLUSION: Re-Implant implants presented a pattern of low, well-distributed stresses along the entire implant-to-bone interface. YPSZ implants had very similar stress distribution to cpTi implants and may be viable esthetic alternatives, especially in maxillary anterior regions.