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Subcrestal placement of implants may have interproximal bone proximity issues that interfere with the submucosal contour of implant-supported zirconia restorations during delivery of the restorations. Modification of the mesial distal submucosal areas may be necessary to fully seat the restoration without impingement of the interproximal bone. Our aim was to determine if modification of submucosal cervical contour of implant supported zirconia-titanium base (Zi-Ti base) restorations resulted in a significant change in fracture strength compared with Zi-Ti base restorations without any modification near the cervical submucosal area. Implant Zi-Ti base restorations designed in the form of a maxillary premolar were made for the Straumann implant lab analog. Zirconia samples were cemented onto the Ti-base and the test group (N = 20) underwent recontouring and polishing at the junction of the Zi-Ti base cervical areas. The control group (N = 20) did not undergo any modifications. All 40 samples underwent fracture testing with an Instron machine. We assessed differences between modified and unmodified implants restorations using a 2-tailed t test for independent samples. Fracture strength values (N) ranged from 4354.68 to 6412.49 in the test group (N = 20) and from 5400.31 to 6953.22 in the control group (N = 20). The average fracture strength in the control group (6154.84 ± 320.50) was higher than in the modified group (5593.13 ± 486.51; P <.001). Modification of submucosal contour significantly decreased fracture strength. However, the average fracture strength exceeded the masticatory forces of humans. [ABSTRACT FROM AUTHOR]

The article presents a case studies of several patient regarding the combination of optical and physical properties of monolithic zirconia restorations. It mentions abutments that allow an angle change and screw-retention abutments and patients with durable and esthetic restorations that can be easily maintained. It also mentions conventional two-dimensional radiography, and three-dimensional cone beam computed tomography and failing restorations and implants.

The article describes a technique to fabricate retrievable screw-retained implant-supported full-arch zirconia fixed dental prostheses. Topics include diagnosis and treatment planning of fixed implant prostheses, transition and surgical phase, and provisional restoration. Important factors to consider in implant-supported restorations fabricated in zirconia are also discussed

The article presents a case study of a 66-year-old male patient presented to the University of Southern California 1 year after receiving full-mouth implant-supported porcelain-fused-to-metal restorations. The patient complained that his restorations showed porcelain chipping and that his teeth were flared out labially. A method of fabricating a retrievable, cross-arch, implant-supported zirconia fixed partial denture (FPD) based on CAD/CAM copy milling has been described.

Objectives: To understand (a) the effects of labial enamel on tooth color (b) relationship of color data taken by nonpolarized (NP), cross‐polarization photography (CP), and spectrophotometry (SP). Materials and methods: Fifty extracted human maxillary incisors were coated with resin on their palatal surfaces. Their color was measured with NP, CP, and SP and their dimensions were scanned by an intraoral scanner. The labial enamel was removed using a modified selective enamel demineralization technique. Tooth dimensions and color were recorded again. The differences in the labial enamel thickness (ΔT) and color (∆E*00 and ∆L*, ∆a*, ∆b*) were statistically analyzed with the Pearson correlation coefficient and simple linear regression. Results: In CP and SP methods, ΔT and ∆E*00 were weakly to moderately positively correlated (r =.38 and.27). In NP, CP, and SP methods, ∆T and ∆b* are weakly positively correlated (r =.27,.27 and.29). The color data of three measuring methods were highly positively correlated (r >.8). A linear relationship between ∆E*00 and ∆T were found (CP and SP groups). Conclusions: (a) Thicker labial enamel has a greater impact on tooth color. (b) Reducing labial enamel thickness shifts the tooth color toward yellow. (c) Tooth color measured from the three methods were highly correlated. Clinical Significance: Knowing the relationship between enamel thickness and tooth color, a clinician can better predict the stump shade before tooth preparation. Due to the highly correlated measuring outcomes, it is reasonable to combine these three methods during shade matching. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the clinical efficacy of implant prostheses retained by screws and cement (SCPs) by examining the reverse torque values (RTVs) of the abutment screws and the marginal openings of the implant prostheses. Materials and Methods: Two implants (3.8 × 13 mm; Camlog Biotechnologies) were embedded in an acrylic resin block 5 mm apart. Eighteen copies of this resin specimen were fabricated and randomly divided into two groups. Two-unit implant prostheses with two different designs—purely cement-retained implant prostheses (group 1) and SCPs (group 2)- were made out of type IV gold alloy and placed on the implants. After tightening to about 30 Ncm, the preloading RTVs of the abutment screws were measured. After retightening the abutment screws or cementing the prostheses, followed by cyclic loading, the postloading RTVs of the abutment screws were examined. Also, the marginal openings of the prostheses in the two groups were measured under a stereomicroscope. These measurements were compared statistically. Results: The postloading RTVs and their differences from the preloading RTVs of the abutment screws demonstrated no significant differences between groups (P > .05). Group 2 prostheses showed significantly smaller marginal openings than group 1 prostheses (P < .05). Conclusion: The forces generated when torquing the abutment screw of the SCP did not cause more loosening of the abutment screws than the purely cementretained implant prosthesis. The SCP showed better marginal adaptation of the cement-retained part than the purely cement-retained implant prosthesis, possibly as a result of the screw-retained abutment seating the restoration. Within the limitations of this in vitro test, the SCP showed no significant difference in RTV of the abutment screw and a smaller marginal gap compared to a purely cement-retained implant prosthesis. [ABSTRACT FROM AUTHOR]

Definite location of the surgical guide is critical to success in prosthetically driven implant dentistry. In edentulous mandibles, precise location of the surgical guide is difficult because of limited nonmobile surfaces. When surgical flaps are raised, this further reduces surfaces for locating the surgical guide. A technique is described in which 3 transitional implants are used to precisely locate the surgical guide then aid in relating the provisional restoration for immediate loading of the implants. Advantages of the technique are described and compared to other methods of locating the surgical guide. [ABSTRACT FROM AUTHOR]

Proper placement and orientation of dental implants is a requirement for the optimum function and esthetics of the definitive restoration. Surgical template stability during the surgical phase is a key element in the success of proper implant placement. Therefore, any clinical tool that enhances the precision of reproduction is of value. This article describes a simple, noninvasive, cost-effective technique for surgical template stabilization utilizing 2 transitional implants placed the same day as the definitive implants. [ABSTRACT FROM AUTHOR]

It may be desirable to extend the working time of poly(vinyl siloxane) impression materials when making a multiple-unit impression. Alteration of the base-catalyst ratio is not possible with automix systems, but chilling the impression material provides an alternative. This study evaluated the dimensional accuracy of chilled impression material and the effect on accuracy of reheating the impression to mouth temperature prior to pouring. Two brands of poly(vinyl siloxane) impression material were evaluated both after refrigeration and at room temperature. Impressions were poured at room temperature and reheated to mouth temperature prior to pouring. Gypsum dies were recovered and measured. Refrigeration had no statistically significant effect on dimensional accuracy. Reheating the impression had no clinically significant effect on accuracy. [ABSTRACT FROM AUTHOR]

Polymerization inhibition of poly(vinyl siloxane) impression materials has been reported with the use of latex gloves. This study evaluated the effect on polymerization of a poly(vinyl siloxane) impression material in both direct and indirect contact with 25 brands of latex gloves, two brands of vinyl gloves, and two weights of rubber dam. Use of all but one of the latex products (96%) resulted in inhibition of polymerization with direct contact. Forty percent of the latex gloves tested inhibited polymerization with indirect contact. The vinyl gloves tested had no effect on polymerization. The implications of inhibited polymerization were discussed. [ABSTRACT FROM AUTHOR]

The setting time, comprehensive strength, diametral tensile strength, expansion, and fine detail reproduction of disinfectant-containing die stones (Steri-Die A and Steri-Die B) were compared to two commonly used die materials (Vel-Mix and Die-Keen). Six samples of each die material were formed from polysulfide rubber, condensation silicone, polyether, and poly(vinyl siloxane) impression materials. The disinfected die stones compared favorably to the controls in all tests with the following exceptions: Steri-Die B was weaker in both compressive and tensile strength and deficient in detail reproduction, especially with condensation polymerizing silicone. [ABSTRACT FROM AUTHOR]

Dilantin sodium is a commonly used anticonvulsive agent. A well-known side effect of this medication is hyperplasia of gingival tissues. This hyperplasia has also been reported in mucosa beneath complete dentures and has been related to poor oral hygiene. This case report describes hyperplasia of tissues around titanium implants in a patient taking Dilantin sodium to prevent epileptic seizures. The excess tissue was removed and hygiene reinforced. NO recurrence of the tissue enlargement is evident after 1 year. [ABSTRACT FROM AUTHOR]

Very high viscosity (putty) poly(vinyl siloxane) impression materials are used with both the conventional double-mix and single-mix putty/wash techniques. When the latter technique is used, portions of the impression of the prepared teeth may be made in the putty rather than the wash material. This study investigated the ability of ten different putty materials to reproduce fine detail. The American Dental Association stainless steel test die for Specification No. 19 was used. Two of the materials consistently reproduced the 20-μm groove. Three of the materials reproduced the 20- μm groove in one-half of the samples tested, while the remainder failed to do so. [ABSTRACT FROM AUTHOR]

The inhibition of polymerization of polyvinyl siloxane impression materials by direct contact with latex gloves has been well documented. Indirect intraoral inhibition of polymerization that results from contact of oral tissues with latex gloves during tooth preparation and gingival retraction procedures has been reported. This case report illustrates the problems that can occur when the dentist used polyvinyl siloxane impression materials while wearing latex gloves. In the reported case, the inhibition is severe and obvious; in most situations the inhibition of polymerization is more subtle and is frequently undetected. Clinicians must be aware of this potential problem and the solution to it. [ABSTRACT FROM AUTHOR]