Biomedical subjects

J R Strub

Publications and source records attributed to J R Strub.

123 records · Page 7Linked to original sources

PubMedDate not supplied

Strength and mode of failure of single implant all-ceramic abutment restorations under static load.

The strength and mode of failure of three different designs of custom-made all-ceramic implant abutments fabricated by milling of In-Ceram sintered ceramic blocks were compared with the conventional CeraOne system under static load. Four test groups were formed with different locations of abutment screws. In three test groups, In-Ceram crowns were fabricated for placement on the all-ceramic abutments, and in one test group, a veneer porcelain was fired directly on the abutment; crowns in the control group were fabricated using the CeraOne system. Ten-mm-long Brånemark implants were placed into a brass block that allowed loading at a 30-degree angle to the long axis. The test group in which the veneer porcelain was fired directly on the all-ceramic abutments was the weakest, and it showed fractures at a mean value of 236 N. The fracture strength of the three other test groups was dependent on the extension of the crown margin relative to the location of the screw head. The test group that had the screw on the top compressing the entire ceramic abutment showed a mean value of 422 N that was similar to the results that were achieved with the CeraOne system (427 N). The weakest link in the all-ceramic single implant restorations was the abutment screw in which the bending began at approximately 190 N.

Aluminum Oxide↗

PubMedDate not supplied

Survival rate and fracture strength of endodontically treated maxillary incisors with moderate defects restored with different post-and-core systems: an in vitro study.

PURPOSE: This study compares the survival rate and fracture strength of endodontically treated maxillary incisors with moderate coronal defects restored with different post-and-core systems after exposure to an artificial mouth. MATERIALS AND METHODS: Sixty-four caries-free human maxillary central incisors were selected for standardized size and quality, endodontically treated, and decoronated 2 mm coronal to the cementoenamel junction. Group 1 was restored with titanium posts and composite cores, group 2 received zirconia posts and a composite core, and in group 3 zirconia posts with a heat-pressed ceramic core were used. Teeth restored with cast posts and cores served as controls. All teeth were prepared and restored with complete cast crowns. All samples were exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling. In addition, the samples were loaded until fracture in a static testing device. RESULTS: The survival rates of the different groups were: 94% for titanium/composite, 63% for zirconia/composite, 100% for the all-ceramic post and core, and 94% for the cast post and core. The following mean fracture strengths were obtained: titanium/composite = 425 +/- 155 N, zirconia/composite = 202 +/- 212 N, zirconia/ceramic = 378 +/- 64 N, cast post and core = 426 +/- 178 N. The lower fracture load in the group with zirconia posts and composite cores was statistically significant. The use of zirconia posts resulted in fewer oblique root fractures. CONCLUSION: Prefabricated titanium posts with composite cores, zirconia posts with heat-pressed ceramic cores, and cast posts and cores yield comparable survival rates and fracture strengths for the restoration of crowned maxillary incisors with moderate coronal defects. Survival rates and fracture strengths for zirconia posts with composite cores are significantly lower, so this combination cannot be recommended for clinical use.

Cementation↗

PubMedDate not supplied

Is there a benefit of using an arbitrary facebow for the fabrication of a stabilization appliance?

PURPOSE: The aim of this clinical study was to evaluate if an arbitrary facebow registration and transfer provides significant advantages for the fabrication of an occlusal appliance in comparison with the omission of such a procedure. MATERIALS AND METHODS: For 20 fully dentate adult patients diagnosed with bruxism, two Michigan occlusal splints were constructed. One of the two upper dental casts was transferred to the articulator with an arbitrary earpiece facebow; the other maxillary cast was mounted arbitrarily using a flat occlusal plane indicator. Upon splint delivery, the number of intraoral occlusal contacts and the time needed for chairside occlusal adjustment were recorded. RESULTS: The number of occlusal contacts on the appliance fabricated with or without facebow was similar in most cases both in the articulator and in the mouth. The one-sided Wilcoxon rank sum test showed with high probability that the use of an arbitrary facebow does not yield a clinically relevant improvement with regard to the number of occlusal contacts or the chairside adjustment time. CONCLUSION: From this pilot study, it appears that for the fabrication of an occlusal appliance, registration and transfer with an arbitrary earpiece facebow does not yield clinically relevant benefits. Of course, this conclusion cannot be transferred to other facebows and is restricted to the levels of clinical relevance defined in the study.

Adult↗

PubMedDate not supplied

Stability of all-porcelain, resin-bonded fixed restorations with different designs: an in vitro study.

The strength of resin-bonded, all-ceramic fixed partial dentures with different framework and prosthesis designs was evaluated. Metal dies were fabricated from a cast of a patient missing the left central incisor and the adjacent teeth were prepared to receive an all-ceramic, resin-bonded prosthesis. Framework designs were standardized and at least 10 samples were made for testing each design. Labial veneering of the pontic with Vitadur-N significantly decreased the stability compared with that of the unveneered In-Ceram framework. Circumferential veneering of the pontic and additional proximal box preparation yielded the strongest units.

Aluminum Oxide↗

PubMedDate not supplied

Combined therapy for teeth with furcation involvement used as abutments for fixed restorations.

Preprosthodontic and prosthodontic procedures for preparing molars with degree 3 furcation involvement for use as abutments for a fixed prosthesis are described. Periodontal surgery precedes endodontic and restorative pretreatment of the abutments, and the required root resection, root separation, or hemisection is performed. A long-term, provisional resin-veneered metal framework restoration is placed for 9 to 12 months. If neither biological nor technical failure occurs, the final metal ceramic fixed restoration may then be fabricated.

Dental Abutments↗

PubMedDate not supplied

Metal ceramic and all-porcelain restorations: current considerations.

A review of the state of the art of metal ceramic and all-porcelain restorations is made. Metal ceramic systems are discussed relative to current fabrication techniques, porcelain margin techniques, marginal adaptation, and esthetics. The material properties, marginal adaptation, and esthetics of all-porcelain restorations are reviewed. Additionally, observations of metal ceramic and all-porcelain restorative systems currently in development are presented.

Ceramics↗

PubMedDate not supplied

In vitro and in vivo evaluation of a new Opaque system for metal ceramic restorations.

This study made an in vitro comparison of the shear strength in a corrosive solution, the scanning electron microscopy of the processing steps, and the x-ray powder diffraction analyses of a newly developed opaque system (Biopaque) with a traditional opaque-system (Opaque P). Clinically, two traditional opaque systems (Opaque P and Vita-VMK-Paint-On 88 opaque) were compared to Biopaque over a 4-year period. A total of 218 metal ceramic units were placed for 29 patients. One hundred ten were veneered with Biopaque, 50 with Opaque P, and 58 with Vita-VMK-Paint-On 88. The technical failure rate of the metal ceramic restorations was 9.6%, and the biological failure rate 5.5%. There was no significant difference of the shear strength in a corrosive solution between Biopaque and the traditional opaque system (Opaque). The x-ray powder diffraction analyses revealed that only the base paste of Biopaque was a newly developed material. In this study, the new opaque system (Biopaque) showed the same in vitro and in vivo results as the other conventional opaque systems. However, at least 5 years of clinical evaluation are necessary before this new opaque system can be completely recommended.

Adult↗

PubMedDate not supplied

Marginal fit of restorations before and after cementation in vivo.

Triturated luting cements provide convenient clinical handling. This study clinically evaluated the influence of two trituration capsule cement systems on the marginal fit of inner copings for telescoping crowns. Using a randomized parallel design, one coping was cemented using zinc phosphate cement (Phosphacap) and one using a glass-ionomer cement (Ketac-Cem Maxicap) for each of 12 patients. A blind examination of the marginal fit of the restorations was made before and after cementation using the replica technique and a scanning electron microscope. The mean marginal discrepancies for all cast copings were approximately 30 microns (median 23 microns) before cementation. They increased significantly after cementation to 86 microns (median 63 microns) in the zinc phosphate cement copings but to only to 47 microns (median 44 microns) in the glass-ionomer cement copings.

Crowns↗

PubMedDate not supplied

Advanced surgical and prosthetic management of the anterior single tooth osseointegrated implant: a case presentation.

The functional and aesthetic rehabilitation of a single missing anterior tooth presents a surgical and prosthetic challenge. This article describes reconstructive and restorative techniques applied to the rehabilitation of such a case, using an osseointegrated implant, guided bone regeneration, mucogingival preprosthetic plastic surgery, and an all-ceramic restoration. The learning objective of this article is to enhance the knowledge of single-tooth implant restorative approaches and procedures.

Adult↗

PubMedDate not supplied

Health human periodontal versus peri-implant gingival tissues: an immunohistochemical differentiation of the extracellular matrix.

Healthy human periodontal and peri-implant (ITI Bonefit) keratinized gingival tissues were studied immunohistochemically to evaluate the possible presence of structural differences in the extracellular matrix protein localization. Collagen types I, III, IV, and VII and fibronectin showed similar distribution in these tissues. Compared to the periodontal tissues, collagen type V was localized in higher amounts in the lamina propria of the peri-implant gingival tissues. Collagen type VI stained the periodontal tissues as a delicate microfibrillar network contrasting to the not well-stained peri-implant gingival tissues. The data show that structural differences between these tissues are present. The structural differences may be responsible for the defense of peri-implant keratinized gingival connective tissues to bacterial penetration, because of the high amount of the collagen type V component, which is responsible for the higher collagenase stability.

Adult↗

PubMedDate not supplied

Inflamed human periodontal versus peri-implant gingival tissues: an immunohistochemical differentiation of the extracellular matrix.

Inflamed human periodontal and peri-implant (ITI Bonefit) gingival tissues were studied immunohistochemically to evaluate the possible presence of structural differences in the extracellular matrix protein localization. Collagen types I, III, IV, V, VI, and VII and fibronectin showed a similar distribution in these tissues. Data show that morphologic structural differences between these inflamed tissues are not present. According to these findings, the connective tissue response of inflamed peri-implant as well as periodontal gingival tissues should be similar during treatment when the inflammation is localized only in the soft tissue level.

Aged↗

PubMedDate not supplied

Finite element analysis of ceramic abutment-restoration combinations for osseointegrated implants.

All-ceramic restorations can solve many esthetic problems associated with implant-supported prostheses. This study evaluated stress concentration and distribution in implant abutments under normal masticatory forces using computer simulations. Two-dimensional finite element analysis was used to study four different abutment-restoration combinations using Brånemark implants. The models considered two positions of the fastening screw, two positions of the crown margins, cemented versus screw-retained prostheses, and clinical loads of 200 N. Models having screws on top of abutments had the lowest stresses (3.1 to 4.8 MPa) and best stress distribution. Screw-retained prostheses and short crown margins increased overall stresses (9.9 to 11.4 MPa).

Aluminum Oxide↗

PubMedDate not supplied

Guided bone regeneration around exposed implants: a new bioresorbable device and bioresorbable membrane pins.

This article presents the principles and the clinical procedure of utilizing a new bioresorbable collagen barrier device, bioresorbable membrane pins, and a new bone substitute for bone regeneration around exposed implants. Three cases are used to illustrate the clinical procedure. In all three cases, the regeneration of bone around the implants was successful, and upon clinical examination the newly regenerated material resembled natural bone. Histologic data regarding the new bioresorbable collagen barrier itself and the time range in which the collagen device functioned as a barrier are still lacking, and the studies are currently being conducted. The learning objective of this article is to introduce a combination of options available for successful regeneration of bone around the implants and avoiding the second-stage surgery.

Adult↗

PubMedDate not supplied

An international comparative multicenter study of assessment of dental appearance using computer-aided image manipulation.

PURPOSE: The aim of the present investigation was to perform an international multicenter comparison of dental appearance as evaluated by dentists, dental technicians, and nondental subjects. MATERIALS AND METHODS: The participants were drawn from three groups: 203 dentists, 197 dental technicians and 254 nondental subjects. The methods developed in a previous study in Sweden were applied again in seven centers located in six countries. A questionnaire, accompanied by five sets of computer-manipulated images portraying one man and one woman, was used to prompt and record responses to different aspects of dental appearance and function. RESULTS: The questionnaire revealed that both the dental appearance and function of teeth were important to most of the participants, but three quarters of the participants did indicate that good dental function was more important that esthetics. More women (30%) than men (18%), however, placed greater importance on appearance. Age or gender did not influence judgments of the computer-manipulated images, although judgments did vary greatly within the three groups and between the centers. Nonetheless, highly colored teeth were preferred more often by nondental subjects than by dentists or dental technicians. CONCLUSION: Computer-aided image manipulation shows promise as a method for investigating the significance of dental-related beliefs, especially those relating to esthetics, in different population groups. The evaluation of dental appearance and function in this study indicated that dental function is held in greater regard, and that the significance of dental appearance varies widely among dentists, dental technicians, and nondental subjects.

Adolescent↗

PubMedDate not supplied

Use of wide-diameter and standard-diameter implants to replace single molars: two case presentations.

PURPOSE: The ultimate goal in modern esthetic dentistry is the restoration of lost hard and soft tissues by imitating nature as closely as possible. With the increasing esthetic awareness of patients, surgical and technical developments, and dentists' enhanced skills and knowledge, optimal function and esthetics are achievable even with implant-supported restorations in molar regions. Anatomic and morphologic factors and poor bone quantity and quality might reduce success rates of dental implants in the posterior jaw. Today, there are two options to replace a single missing molar by an implant-supported crown: the single wide-diameter implant or two standard-diameter implants. These two approaches are described and their advantages and disadvantages discussed in two exemplary clinical cases. MATERIALS AND METHODS: In one case, the edentulous ridge in the area of the mandibular right first molar (FDI tooth 46) provided sufficient mesiodistal space to restore tooth 46 with a porcelain-fused-to-metal crown on two standard-diameter implants, placed in a root-analog manner. In the other case, the manibular first molars (FDI teeth 36 and 46) were replaced by porcelain-fused-to-metal crowns on wide-diameter implants. RESULTS: It can be concluded that both options to replace a single molar provide more surface area and better biomechanical properties than one standard implant. CONCLUSION: Long-term data are needed before these treatment modalities can be recommended for the private practitioner.

Adult↗