The effect of abutment dis/reconnections on peri-implant bone resorption: a radiologic study of platform-switched and non-platform-switched implants placed in animals.

OBJECTIVES: The purpose of this animal study was to radiologically measure the influence of abutment disconnection on bone resorption and to compare this influence on platform-switched vs. non-platform-switched implants. METHODS: The study design included extraction of all mandibular premolars in five canines . After 2 months, six implants were placed in each dog. Four of them were platform-switched (PS) implants and two were non-platform-switched (NPS) implants. Some or all of the abutments connected to the implants were disconnected at pre-ordained post-surgical intervals. Radiographs were taken at the time of implant placement and at every handling. The values for mesial (horizontal and vertical) and distal (horizontal and vertical) bone resorption were taken and compared for each implant at every abutment dis/reconnection. RESULTS: The average vertical bone resorption around NPS implants after four dis/reconnections was 1.09 mm (SD 0.25 mm), and the average horizontal bone resorption was 0.98 mm (SD 0.27 mm). The average vertical bone resorption around PS implants after four dis/reconnections was 0.24 mm, (SD 0.08 mm) and the average horizontal bone resorption was 0.24 mm (SD 0.13 mm). The difference of the average horizontal and vertical bone resorption around NPS (site D) and PS (site A) implants was statically significant (P < 0.05). The average mesial and distal bone resorption values around PS (site A) implant adjacent to a tooth were compared, and statically significant differences were found (P < 0.05). CONCLUSIONS: Implants with a PS design show less peri-implant bone resorption during the healing process and as their abutments are disconnected, than do comparably dis/reconnected NPS implants. The location of the PS implant next to a tooth may decrease radiographically visible peri-implant bone resorption significantly.

Cutting-Edge Implant Rehabilitation Design and Management: A Tapered Abutment Approach.

Soft-tissue recession around an implant rehabilitation over time has been considered a physiologic phenomenon. The divergent profile of the abutment and the abutment's dis/reconnections are the most critical predisposing and precipitating factors regarding such gingival recession. Recent publications have discussed how tapered and marginless abutments that allow no disconnections and increase soft-tissue thickness could prevent implant rehabilitations from experiencing gingival recession. The objective of this article is to demonstrate the biologic rationale of tissue behavior surrounding tapered abutments and their clinical application.

Modified surgical protocol for placing implants in the pterygomaxillary region: clinical and radiologic study of 454 implants.

PURPOSE: To review a series of 454 pterygoid implants placed more vertically than the previous standard angle (45 degrees) over a functional loading period ranging from 2 months to 14 years with a mean follow-up period of 6 years. MATERIALS AND METHODS: A retrospective study was made. The sample was composed of patients rehabilitated with pterygoid implants between January 1997 and December 2010. Patient selection criteria included: edentulism on the posterior area of an atrophic maxilla, with less than 8 mm remaining from the sinus floor to the alveolar crest, and the presence of an anterior implant or tooth to ensure mesial support for a partial denture. After a healing period between 2 and 7 months, panoramic x-rays were taken at the time of loading. The implant length, implant diameter, implant success, and the angulation of the pterygoid implants were measured. RESULTS: Three hundred ninety-two patients (206 women and 186 men) ranging in age from 34 to 75 years were fitted with 454 pterygoid implants and followed up. The 18-mm implant length was the most favored implant to fit in the pterygoid area. Implant diameter was 3.75 mm in 448 cases (98.6%). The mean mesiodistal angulation of the pterygoid implants was 70.4 degrees±7.2. After a mean follow-up period of 6 years, 96.5% of the implants placed were successfully osseointegrated. CONCLUSIONS: The findings indicate that a mesiodistal inclination of the pterygoid implant at 70 degrees relative to the Frankfort plane following the bony column of the pterygoid region decreases the non-axial loads of the rehabilitations and exhibits good long-term survival; however, further studies are needed to assess the long-term survival of implants in the pterygomaxillary region.

Crestal bone changes on platform-switched implants and adjacent teeth when the tooth-implant distance is less than 1.5 mm.

Because of the peri-implant bone resorption that occurs when a non-platform switched implant is exposed to the oral environment, it has been recommended to maintain 1.5 mm between the tooth and implant to preserve the bone adjacent to the teeth. Several studies have documented that platform-switched implants have less peri-implant bone resorption than matched implants. This retrospective radiographic analysis studied 70 platform-switched implants placed less than 1.5 mm from an adjacent tooth and with prostheses loaded for a minimum of 6 months. The mean distance between the implant and tooth was 0.99 mm (range, 0.20 to 1.49 mm); the mean horizontal and vertical bone resorption was 0.36 and 0.43 mm, respectively. The mean bone peak reduction was 0.37 mm. The results confirm that the use of platform-switched implants reduces bone resorption after two-piece implants have been uncovered and that it is possible to place this type of implant 1 mm from teeth while maintaining the bone level adjacent to them (the bone peak).

Soft tissue remodeling technique as a non-invasive alternative to second implant surgery.

It is currently accepted that success in implant-supported restorations is based not only on osseointegration, but also on achieving the esthetic outcome of natural teeth and healthy soft tissues. The socalled "pink esthetic" has become the main challenge with implant-supported rehabilitations in the anterior area. This is especially difficult in the cases with two adjacent implants. Two components affect the final periimplant gingiva: a correct bone support, and a sufficient quantity and quality of soft tissues. Several papers have emphasized the need to regenerate and preserve the bone after extractions, or after the exposure of the implants to the oral environment. The classical implantation protocol entails entering the working area several times and always involves the surgical manipulation of peri-implant tissues. Careful surgical handling of the soft tissues when exposing the implants and placing the healing abutments (second surgery) helps the clinician to obtain the best possible results, but even so there is a loss of volume of the tissues as they become weaker and more rigid after each procedure. The present study proposes a new protocol that includes the connective tissue graft placement and the soft tissues remodeling technique, which is based on the use of the ovoid pontics. This technique may help to minimize the logical scar reaction after the second surgery and to improve the final emergence profile.