In this article, root implants implanted directly after extraction of the natural teeth were described. The root implants were made of densely sintered or hot-pressed calcium hydroxylapatite (CHA). The significance of using such implants as a method of preserving the bulk of the alveolar ridge and as possible anchoring sites for a post and core for fixed partial dentures was discussed.

Immediate dental root implants from synthetic dense calcium hydroxylapatite.

Current Evaluation of Dental Implants

The purpose of this article was to review and summarize the literature on the retention of submerged roots. It appears that the submerged-root procedures may have an accepted place alongside conventional overdenture techniques in the profession's continuing effort to retard alveolar bone resorption in the field of prosthodontics.

A review of the submerged-root concept

This investigation of standard curing methods for PMMA implants has demonstrated that alternate means of using the air oven may produce good strength properties along with a considerable degree of porosity, when desired, in a relatively short period of time. Curing of polymers in a pressure pot offers few advantages owing to the length of time required to produce, at best, equivalent strength for the porous materials. The method also poses dangers inherent in the use of superheated salt solution or hot glycerin. The autoclave is widely used in dental offices for sterilizing and will fully and consistently cure polymers within 30 minutes. The best properties for the PMMA resin were achieved with this method (61 MPa or 9,130 p.s.i., tensile strength). The microwave oven has become relatively inexpensive in recent years, and it offers time savings of up to 90 per cent which would be beneficial in implant dentistry or in dental laboratory procedures in general. The exact condition for curing particular polymers must be carefully determined to adjust the time of irradiation in order not to under- or overcure the polymer object. Curing polymers which contain intrinsic foaming agents under pressure conditions slightly reduced the total pore volume. But, pore volume and pore diameter in the large-bead polymers are determined predominantly by packing conditions, not curing conditions. Biologic tolerance to materials cured by these methods in primates is presently being evaluated.

Effect of rapid curing procedures on polymer implant materials

A study was conducted to determine if root implants might delay, halt, or alter normal changes in the pattern of bone resorption following the extraction of teeth. The four projects involved two biologic and two nonbiologic types of implants. The morphologic changes recorded showed delayed or altered resorption patterns. The implants tested (except plaster of Paris) proved to be tolerated by the tissues. The findings indicate that the implants act as space fillers and seem to yield some mechanical support to the labial and palatal plates of bone. Future projects should include implants that would also contribute to the reconstruction of the tooth socket, the implants eventually being resorbed and the space filled by new bone.

Effect of root implants on resorption of residual ridges.

An investigation was developed to test the clinical possibilities of a method to preserve the residual alveolar bone immediately following tooth extractions. Clinical observations of bone stability over retained roots or teeth led to this study. Observations showed that resorption proceeds at a slower rate over the implant area and that the presence of the implant did minimize the amount of bone loss over the period observed. The nagging fear of the development of malignancy through the use of acrylic resins has caused the temporary withdrawal of an otherwise handy and practical material from future phases of this investigation. It is hoped similarly based investigations using roots of the extracted teeth themselves as implants will be continued. Primary union of the oral tissue over the open socket is an important factor for success. The positioning of the implants (3 mm. or more below the infraalveolar bone crest) appears as a factor in the success of the implant and the organization of the blood clot. Future investigations must bear these important features in mind.

Acrylic resin root implants: A preliminary report

Summary A continuing report of the effect of acrylic resin root implants on the preservation of the alveolar process or the prevention of its loss subsequent to tooth extractions was presented. This report was made 20 months after the insertion of the acrylic resin root implants and the contour changes both labially and palatally were presented together with radiographs of the implants with the bony changes observed. The presence of the resin implants seems to lessen the contour changes occurring over the period of observation both on the labial and palatal surfaces as compared with the control sites. The radiographs suggest the implants are now “sealed” within a bony framework. The absence of clinical manifestations of pathology at any stage of the 20 month period seems to indicate a favorable acceptance of the implants by the tissues.

K.Y. Poon

Papers

Acrylic resin root implants: A preliminary report

Acrylic resin root implants: A continuing report