The Conometric Concept: Definitive Rehabilitation of a Single Posterior Implant Using a Friction Retention Abutment. A 1-year Follow-up Report

PURPOSE: To provide a 1-year assessment of friction-retention abutments (Acuris, Dentsply Sirona) used to retain a single lithium disilicate (LS2) monolithic restoration. MATERIALS AND METHODS: A total of 522 implants were placed to treat single-tooth premolar and molar edentulous sites in the mandible or maxilla. Three types of implants were used. The tested abutments were connected 3 months after implant placement. A single pressed LS2 monolithic restoration was cemented to a dedicated titanium cap and engaged to the abutment without the use of screws or cement. Any complications affecting the restoration or the opposing dentition, soft tissue dimensional changes, the distance between the implant platform and the bone peak, and pocket probing depths were recorded at the time of restoration placement (T0), after 6 months of function (T1), and after 1 year of function (T2). Esthetic, functional, and biologic parameters were recorded at T0 and T2. RESULTS: A total of 507 patients (284 women and 223 men) received a restoration (T0), and 504 of them reached the T2 1-year follow-up. One restoration fractured after 10 months in function. No statistically significant difference was assessed in the soft tissue measurements or in the measurements of the distance between the supporting implant platform and the bone peak. None of the restorations detached during the observation period. CONCLUSION: The friction retention abutment is a viable option to retain an implant-supported monolithic LS2 glass-ceramic restoration in cases of premolar or molar single-tooth edentulism.

Fixed Partial Restorations Made of a New Zirconia-Reinforced Lithium Silicate Material: A 2-Year Short-Term Report.

PURPOSE: To evaluate the 2-year performance of definitive implant- or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate placed to restore premolars and molars in clinical cases of partial edentulism. MATERIALS AND METHODS: All patients received a three-unit fixed restoration made of monolithic, hot-pressed, zirconia-reinforced lithium silicate glass-ceramic. The restoration was cemented to two natural teeth or attached to two 3.5- or 4.5-mm-diameter square threaded, grit-blasted, acid-etched integrated implants with a Morse taper connection. Peri-implant pocket depth and bone and soft tissue remodeling were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the World Dental Federation study design were assessed yearly until the final follow-up appointment. At the time of placement of the definitive restorations and at the 2-year follow-up visit, the opposing dentitions were identified by type of restoration and supporting structures. RESULTS: A total of 100 patients were consecutively enrolled in the period between June 2016 and July 2017, and 50 patients each received an implant-supported restoration (Group A) or a tooth-supported restoration (Group B). One (2%) of the 50 implant-supported prostheses fractured after 21 months of function. None of the other prostheses failed or became loose or detached. No significant differences involving probing levels or bone and soft tissue remodeling were found between the follow-up times. No cases of inflammation or infection of the mucosal cuff around the neck of the implants were recorded. The most common issue occurred immediately after placement of the prosthesis, when 3 patients (6%) from Group A and 4 patients (8%) from Group B asked for a modification of tooth shade. CONCLUSION: Implant-supported or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate can be used to successfully restore cases of posterior partial edentulism. The 2-year results of this report will be studied more in depth in ongoing long-term research.

The conometric concept for the definitive rehabilitation of a single posterior implant by using a conical indexed abutment: A technique.

This report describes the restoration of the healed single implant in the posterior region by using a lithium disilicate crown supported by an Acuris abutment. The restored implants were placed in the premolar and molar region of both the mandible and the maxilla by using a 1-stage approach. The definitive Acuris abutment was placed after an implant healing period of at least 3 months. Definitive impressions were made at least 3 months after surgery. The precrystallized lithium disilicate crown was adapted to a laboratory abutment and evaluated. The crown was then crystallized, finished, colored, and cemented to the definitive abutment by using an adhesive resin cement. The definitive restoration engaged the abutment without the use of screws or cement. A single healed implant can be successfully restored by using a lithium disilicate restoration supported by an Acuris abutment.

The Conometric Concept: A Two-Year Follow-Up of Fixed Partial CEREC Restorations Supported By Cone-In-Cone Abutments.

PURPOSE: To evaluate the performance of definitive, implant-supported, lithium disilicate fixed dental prostheses (LS2 FDPs) manufactured with a computer-assisted design/computer-assisted manufacturing (CAD/CAM) system. All patients received two-unit restorations placed in posterior regions, supported by osseointegrated implants with cone-in-cone connection abutments. MATERIALS AND METHODS: Two implants (Ankylos) were placed into healed sites or fresh extraction sockets in the maxillary/mandibular posterior regions of partially edentulous patients. Definitive digital impressions were made 3 months after surgery. Twenty-four patients received fixed  monolithic LS2 restorations manufactured with the CEREC system. All restorations were connected to the implants using cone-in-cone connection abutments. Peri-implant pocket depths were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed yearly until the last follow-up appointment. The opposing dentitions were identified by type of restoration and supporting structures at the time of placement of the definitive restorations and at the 2-year follow-up visits. RESULTS: One patient (4.16%) moved to an unknown location during the study. A total of 23 FDPs (95.8%) supported by 46 implants reached the 2-year follow-up. None of the prostheses failed, or became loose or detached. No significant difference involving probing levels between the experimental times were found. CONCLUSIONS: The results of this research indicated that the abutment-prostheses connection using a cone-in-cone approach was successful within the 2-year period of this study. None of the studied monolithic LS2 glass-ceramic prostheses milled using the CEREC CAD/CAM system fractured or became detached.

Experimental evaluation in rabbits of the effects of thread concavities in bone formation with different titanium implant surfaces.

BACKGROUND: Differences in implant microtexture are important in conditioning the bone response around dental implants. PURPOSE: The aim of the present study was an evaluation of the bone response in machined (M), blasted with apatitic calcium phosphate (tricalcium phosphate/hydrossyapatite [HA] blend) particles (resorbable blast texturing [RBT]), and coated with HA implants. METHODS: A total of 48 (16 M, 16 RBT, and 16 HA) threaded screw-shaped implants were inserted into the tibia of 12 rabbits. The specimens were retrieved after 1, 2, 4, and 8 weeks and processed for histology. RESULTS: All experimental groups showed an increase of the bone-implant contact percentages through the study period. Higher and highly statistically significant differences were found in the percentages of bone observed in the concavities rather than in the convexities of the implants retrieved after 1, 2, and 4 weeks, while no significant differences were found after 8 weeks. In the different time periods, higher percentages of bone-implant contact were found in the RBT and HA-coated implants both in the concavities and in the convexities, but these differences were not statistically significant. CONCLUSIONS: The newly formed bone present in the concavity of the threads was not influenced by the implant surface in the first healing period, while after 4 to 8 weeks, the percentage of bone observed in the concavities and convexities was similar. Additional histological studies are necessary to further evaluate the critical role of the concave geometry in bone differentiation and formation around dental implants.

Blood vessels are concentrated within the implant surface concavities: a histologic study in rabbit tibia.

Angiogenesis plays a key role in bone formation and maintenance. Bone formation has been reported to initiate in the concavities rather than the convexities in a hydroxyapatite substratum and the implant threads of dental implants. The aim of the present study was to evaluate the number of the blood vessels inside the concavities and around the convexities of the threads of implants in a rabbit tibia model. A total of 32 thread-shaped implants blasted with apatitic calcium phosphate (TCP/HA blend) (Resorbable Blast Texturing, RBT) (Maestro, BioHorizons(®), Birmingham, AL, USA) were inserted in 8 rabbits. Each rabbit received 4 implants, 2 in the right and 2 in left tibia. Implants were retrieved after 1, 2, 4, and 8 weeks and treated to obtain thin ground sections. Statistically significant differences were found in the number of vessels that had formed in the concavities rather than the convexities of the implants after 1 (p = 0.000), and 2 weeks (p = 0.000), whilst no significant differences after 4 (p = 0.546) and 8 weeks (p = 0.275) were detected. The present results supported the hypothesis that blood vessel formation was stimulated by the presence of the concavities, which may provide a suitable environment in which mechanical forces, concentrations and gradients of chemotactic molecules and blood clot retention may all drive vascular and bone cell migration.