Continuous Scan Strategy (CSS): A Novel Technique to Improve the Accuracy of Intraoral Digital Impressions.

PURPOSE: To present the results obtained with the "Continuous Scan Strategy" (CSS), a direct intraoral scanning technique based on the connection of the implant scan bodies (SBs) with thermoplastic resin. METHODS: 40 patients were restored with 45 long-span monolithic implant-supported zirconia restorations (10 partial prostheses [PP] and 35 full arches [FA]) fabricated via a full-digital workflow after the capture of an intraoral impression (Trios3®) using the CSS technique. The primary outcomes were the marginal adaptation and passive fit of the superstructures, checked at T0 (intraoral try-in of polyurethane or metal replica of the final prosthesis) and T1 (delivery of the final zirconia restoration). The secondary outcomes, registered at T2 (2 years after the delivery of the final prosthesis), were implant survival, prosthetic success, and complications. A throughout statistical analysis was performed. RESULTS: At T0, 40/45 replicas demonstrated a perfect passive fit and adaptation. At T1, one prosthesis had fractured, and at T2, an additional prosthesis had fractured and one had chipped. The implant survival rate was 100%. The prosthetic success was 93.3%. CONCLUSIONS: CSS seems to represent a viable option for capturing accurate intraoral digital impressions for the fabrication of precise long-span implant-supported restorations.

Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (p<0.001); however, the thickness of ceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (p<0.05). There was no significant difference in fracture resistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

The effect of tooth-preparation cleansing protocol on the bond strength of self-adhesive resin cement to dentin contaminated with a hemostatic agent.

This study evaluated the effect of tooth-preparation cleansing protocols on the bond strength of a self-adhesive resin cement to dentin contaminated with two different types of hemostatic agents. The occlusal surface of extracted third molars was flattened to expose the dentin surface and prepared for a full crown. Acrylic temporary crowns were fabricated and placed using temporary cement. The specimens were stored at 100% relative humidity for seven days. Following removal of the temporary crowns, the specimens were surface debrided using aluminum oxide abrasion with a particle size of 27 µm at 40 psi. The specimens were randomly assigned to three groups, according to the hemostatic agents: Group I­an agent containing aluminum chloride was applied to the tooth surface; Group II­an agent containing ferric sulfate was applied to the tooth surface and Group III­uncontaminated (control). The contaminated specimens were then further subdivided into three subgroups (A­C; n=12): Group A­tooth surface cleansing with water spray; Group B­tooth surface cleansing with phosphoric acid etch and Group C­tooth surface cleansing with aluminum oxide abrasion with a particle size of 27 µm at 40 psi. Ceramic blocks were treated with a 9.5% hydrofluoric acid-etch and silanized prior to being cemented with self-adhesive resin luting agent (RelyX Unicem) to the prepared dentin. The shear bond strength was determined at a crosshead speed of 0.5 mm/minute. The data were analyzed with two-way ANOVA, followed by the Duncan multiple range test, to determine any significant differences between the testing groups. The microstructure morphology of the tooth surface was evaluated using SEM analysis. The results revealed that there was a significant difference between the bond strength of the control and the contaminated testing groups (p<0.05). A tooth preparation cleansing protocol using particle abrasion with low-pressure aluminum oxide particles provided a significant improvement in bond strength to contaminated dentin, while rinsing with water spray resulted in the lowest mean bond strength of the self-adhesive resin cement to dentin (p<0.05).

Alternative uses of a visible light-polymerized material.

Three different procedures that involve the use of Triad gel are described. This light-polymerized resin material is versatile and easy to use in the dental clinic and laboratory. The procedures described include the transfer of ridge topography for ovate pontic sites, implant lab analog fixation, and solid/soft tissue cast fabrication.

Alternative uses of a visible light-polymerized material.

Three different procedures that involve the use of Triad gel are described. This light-polymerized resin material is versatile and easy to use in the dental clinic and laboratory. The procedures described include the transfer of ridge topography for ovate pontic sites, implant lab analog fixation, and solid/soft tissue cast fabrication.

Predictable single tooth peri-implant esthetics: five diagnostic keys.

The creation of an esthetic implant restoration with gingival architecture that harmonizes with the adjacent dentition is a formidable challenge. The predictability of the peri-implant esthetic outcome may ultimately be determined by the patient's own presenting anatomy rather than the clinician's ability to manage state-of-the-art procedures. To more accurately predict the peri-implant esthetic outcome before removing a failing tooth, five diagnostic keys are discussed. These keys include relative tooth position, form of the periodontium, biotype of the periodontium, tooth shape, and position of the osseous crest.

Predictable peri-implant gingival aesthetics: surgical and prosthodontic rationales.

Bone resorption following maxillary anterior tooth extraction is common and often compromises gingival tissue levels for the implant restoration. The creation of predictable peri-implant aesthetics requires proper understanding and preservation of the osseous and gingival tissue surrounding the failing tooth. This article addresses the various factors that affect the predictability of peri-implant gingival aesthetics in anterior single-tooth replacement. The surgical and prosthodontic procedures for maintenance of peri-implant aesthetics are also presented using an ovate pontic tooth on a removable partial denture following immediate extraction and implant placement.

Fracture load and mode of failure of ceramic veneers with different preparations.

STATEMENT OF PROBLEM: Fracture is a clinical failure modality for ceramic veneers. Whether design of tooth preparation can affect the strength of ceramic veneers remains controversial. PURPOSE: This in vitro study evaluated fracture load and mode of failure of ceramic veneers, with 4 tooth preparation designs, that were bonded on extracted human maxillary central incisors. Identical parameters were also measured on unrestored intact teeth for comparison. MATERIAL AND METHODS: Fifty maxillary central incisors were randomly divided into 5 equal groups. Each group was assigned a different tooth preparation design: (1) no incisal reduction, (2) 2 mm incisal reduction without palatal chamfer (butt joint), (3) 1 mm incisal reduction and 1 mm height palatal chamfer, (4) 4 mm incisal reduction and 1 mm height palatal chamfer, and (5) unrestored (control). Forty teeth were prepared to accommodate ceramic veneers of equal thickness and incisocervical length. Stone dies were fabricated and veneers made from IPS Empress ceramic. Ceramic veneers were bonded and all teeth mounted in phenolic rings with epoxy resin. Fracture loads were recorded with a mechanical testing machine. RESULTS: Mean fracture loads (SD) in kgf were as follows: group 1, 23.7 (6.11); group 2, 27.4 (9.63); group 3, 16.4 (3.44); group 4, 19.2 (6.18); and group 5, 31.0 (10.38). Modes of failure were also analyzed for both ceramic veneers and teeth. One-way ANOVA with multiple comparisons revealed 3 significant subsets: groups 1-2-5, groups 4-1, and groups 3-4 (P <.05). Groups 1 and 2 had no ceramic veneer fractures; group 3 had 3 ceramic veneer fractures, and group 4 had 6 ceramic veneer fractures. CONCLUSION: Groups 1 and 2 recorded the greatest fracture loads that were comparable to an unrestored control.

Restorative dentistry using a multidisciplinary approach.

Multidisciplinary treatment was essential for this patient to optimally manage the occlusion and missing teeth. When the space distribution was completed, ridge management procedures for pontic site development were accomplished. The final restorative treatment required was actually minimized to a 7-unit fixed partial denture. It was apparent the multidisciplinary treatment was essential to predictably manage this patient by decreasing risk and ensuring a long-term strategy for enhanced patient satisfaction.

New paradigms for anterior tooth preparation. Rationale and technique.

A biologic and esthetic rationale has been presented along with a simplified controlled technique to achieve predictable results (Figures 13A and 13B). The clinician is constantly faced with the challenge of developing room for esthetic material while preserving the biologic objectives. Using the three essential anterior tooth preparation keys (incisal edge, reduction requirements, and the biologic zone) enhances predictability. Developing the incisal edge relative to the dynamics of facial esthetics provides the initial starting point of tooth preparation. The reduction requirements are designed to satisfy the mechanical principles, address the pulpal concerns, and preserve the structural requirements of the tooth. The biologic zone can be developed by using the total dentogingival complex measurements and will clinically aid in the determination of cervical limitations to providing intracrevicular margin location.

Aesthetic peri-implant site development. The restorative connection.

The understanding of the relationship between hard tissue, soft tissue, and tooth position is critical for the fabrication of an aesthetic implant restoration. The biology as well as the mechanics of each patient's situation should be evaluated and used to its maximal potential to support the surrounding tissues. Implant sites should be assessed before and after loss of tooth to help maintain the site in a state of aesthetic predictability. If the site deters from the ideal, procedures using orthodontics, bone grafting, or soft tissue grafting should be instituted to receive a well-placed implant. These procedures facilitate the placement of a restoration that harmonizes with the adjacent dentition.

Complete denture impressioning technique.

This article describes a technique that simplifies the making of an edentulous arch impression before the fabrication of a complete denture. Making an impression of an edentulous arch requires a unique combination of managing movable soft tissue commensurate with integrating different materials and a technique for accurate reproduction. The technique described requires a two-phase approach using a syringeable addition silicone during the border molding process and a condensation silicone wash material to capture the soft tissue while the functional border molding is repeated. These more recently developed products allow us to achieve similar results and are easier, faster, and more predictable than those products used previously.