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    In 1982, Gerald A. Niznick, DDS, MSD, established Core-Vent Corporation to market the Core-Vent® implant [Fig. 1], a hollow basket implant design with external threads. The implant was made of medical grade titanium alloy with a grit-blasted surface. It featured an internal hexagon that was used to insert the implant, then served as a receptacle for a variety of cemented abutments. The implant body was provided in three diameters, 3.5mm, 4.5mm and 5.5mm, and featured three threads that projected out from the implant body an additional 0.8mm.

    The wide-diameter Core-Vents predated wide-diameter implants from other major manufacturers by 10 years, and made Core-Vent well suited for immediate placement. The Core-Vent System was the first to offer a variety of abutment options and the first to use free-standing implants for overdenture retention (Niznick GA: J Oral Implantol 1982;10[3]:2-39).

    Evolution of the Screw-Vent and Competing Internal Connection Implants: The Screw-Vent continued to evolve from 1986 through 2000. It was first offered in grade 1 commercially pure titanium, but is now offered in titanium alloy. New Screw-Vent diameters and surface options have also been introduced. By 2000, the implant ultimately evolved into the Tapered Screw-Vent with triple lead threads. This new design further simplifies insertion and increases initial stability in soft bone by a patented surgical protocol of inserting the tapered implant into a straight socket.

    1987 Micro-Vent Implant: To meet the need for a small-diameter implant, Dr. Niznick introduced the 3.25mm diameter Micro-Vent® implant [Fig. 1]. The Micro-Vent features a series of ledges for bone ingrowth, and three apical threads.

    This design provides a unique push-in/screw-in surgical protocol for use in porous maxillary bone. The Micro-Vent was the first commercially available HA-coated implant with threads. Dr. Niznick also introduced the externally hexed Swede-Vent™ implant the same year, which was a clone of the Brånemark implant, but with an acid-etched surface

    1989 Bio-Vent Implant: Dr. Niznick introduced the Bio-Vent® [Fig. 1], an HA-coated cylinder implant. Patented vertical grooves connecting to apical vents were designed to facilitate seating and allow bone ingrowth to prevent rotation.

    1990-1991 Fixture Mount Packaging and VA Research of the Spectra-System: In 1990, all of the Core-Vent, Screw-Vent, Micro-Vent and Bio-Vent implant options featured the internal hexagon-and-thread connection and were packaged in a new sterile delivery system featuring a Titanium Fixture Mount. The philosophies of all four implant designs were synthesized into a protocol for implant selection based on bone quality and location, and the implants were relaunched as the Spectra-System®.

    In 1991, the U.S. Department of Veterans Affairs launched a prospective, multi-center study to determine the influence of implant design and bone location on implant success. The Spectra-System was selected for the study, due to its various design, material and surface options. The V.A. study comprised more than 800 patients and over 100 investigators at 30 V.A. medical centers and two university dental schools. A total of 2795 Spectra-System implants were placed. Based on the results of the V.A. study, the design, material, surface and surgical protocol of the Screw-Vent implant were subsequently changed to better address the differing requirements of hard and soft bone.

    1991-1997 Dentsply Distribution Era and Beyond: From May of 1991 to April of 1997, Dr. Niznick engaged Dentsply International as the sole distributor of Core-Vent Corporation's products, which were continuously developed and manufactured by Dr. Gerald Niznick through Core-Vent Bio-Engineering. In 1992, Dr. Niznick developed the friction-fit connection between the abutment and internal hex implant by tapering the male hex of the abutment. In 1995, this concept of zero rotation and zero tipping movements was also developed for external hex connections by tapering the external hex the Swede-Vent implant. This design, called the Swede-Vent TL, was made of work-hardened, grade 4, commercially pure titanium for maximum strength.

    When Dr. Niznick reassumed control of Core-Vent's product line from Dentsply International, he established Paragon Implant Company as its sole distribution agent. Since that time, Paragon Implant Company and Core-Vent Bio-Engineering have introduced a number of Dr. Niznick's innovative new products. The same year, 3.3mmD and 4.7mmD external hex Swede-Vent TL implants were introduced. Together with the 4.0mmD Swede-Vent TL, the expanded product line featured a common 4.1mmD platform with the patented tapered external hex, and was reintroduced as the Taper-Lock™ Implant System. Today, the Taper-Lock line is offered with SBM-blasted and HA-coated surface options. Also in 1997, Paragon launched one-stage Healing Collar Packing for internal and external hex implants. This packaging option implant had been developed and field tested over the previous three years, but never marketed by Dentsply.

    In 1998, Dr. Niznick introduced another one-stage design, the Complete implant, which was engineered to serve as both the implant and the abutment for screw-retained restorations. Also that year, the body of the Micro-Vent implant was changed to a tapered design with a new patented surface treatment, called Dual Transition Selective Surface [Fig. 1], which features a blasted zone between the smooth neck and the HA coated body. The apical end was left uncoated to facilitate self-tapping insertion. The new design was introduced as the Micro-Vent2™ implant.

    In 1999, Dr. Niznick developed the AdVent implant, which is packaged with an implant extender for one- or two-stage surgery. This design combines the advantages of both the Healing Collar Packaging and Complete Implant System that it replaced. The Advent has the added advantages of a tapered body with triple lead threads. Together, these features speed insertion and expand soft bone for increased initial stability.

    In 2000, the design advantages of the AdVent’s tapered body and triple lead threads were incorporated into the design of the two-stage Tapered Screw-Vent implant. A 6mm-diameter Tapered Screw-Vent option was also introduced, which expanded the versatility of Paragon’s most popular implant. With the tapered design, there is no need for a 3.3mm diameter implant option. The narrow end of the 3.7mm diameter Tapered Screw-Vent can initiate insertion into a socket prepared with the 2.8mm diameter drill used as the final drill for the 3.3mm diameter straight Screw-Vent. The Dual Transition Selective Surface developed for the tapered Micro-Vent2 implant was incorporated into both the AdVent and Tapered Screw-Vent designs, which are Paragon’s premium implant lines.

    The triple lead threads over the body of the Tapered Screw-Vent allow insertion as fast and easy as the push-in/screw-in protocol for the Micro-Vent and Micro-Vent2 implants, which feature a unique combination of ledges and apical threads. In addition, the fully threaded body of the Tapered Screw-Vent provides greater initial stability that is desirable to allow stage-one transfer impressions with the new fixture-mount/transfer/temporary abutments that the Screw-Vent, Micro-Vent and Taper-Lock implants have provided since 1999. For these reasons, the Tapered Screw-Vent will eventually replace the tapered Micro-Vent2. The surgical protocol for the AdVent and Tapered Screw-Vent implants allows implementation of a patented surgical protocol developed by Dr. Niznick in 1996, which expands soft bone by placing the tapered implant implant body into a socket prepared with a straight drill. Unlike other tapered implants that use a matching tapered drill, one straight drill can be used for all lengths of the implants, which reduces the number of instruments that are needed in a system.

    TRADEMARKS: Core-Vent, SwissPlus, Screw-Vent, Advent, Bio-Vent, Micro-Vent, Friction-Fit, Dual Transition Selective Surface are now Implant Trademarks of Zimmer Dental Implant Company 1900 Aston Avenue, Carlsbad, CA 92008. Replace Select is a trademark of Nobel Biocare