Immediate implant in fresh extraction socket of resected mandibular first molar: a preliminary clinical report.

This study presents a new technique that involves resection of the affected mesial root in a lower mandibular molar with immediate implant placement in its extraction socket. This technique offers a treatment option for mandibular molars affected by local periapical infection, bifurcation involvement, or buccolingual fractures. Extraction of such molars usually creates a large edentulous span and subsequent restorative problems. The patient is provided with a crown that is supported by an implant in the resected mesial root site and the retained distal root. The crown is esthetic and functional and easy to maintain. This technique was successfully applied on five patients.

Effect of splinting on load distribution of extracoronal attachment with distal extension prosthesis in vitro.

Previous reports have suggested that the restoration of distal extension edentulous areas with an extracoronal precision attachment partial denture necessitates splinting of abutments. However, the number of splinted teeth remains controversial. In this study, strain gauge technology was used to monitor stresses induced around the abutment and in the distal extension area under different loads as a function of the number of splinted abutments. Three strain gauges were installed in the outer buccal, lingual, and distal surfaces of the abutment to record stresses in the three planes of motion, and another gauge was placed under the distal extension base. The reduction of the number of splinted units from three to two resulted in an insignificant increase of stresses recorded, whereas reduction of the number from two to one resulted in a significant increase of stresses nine times greater than the three-unit splint values. On the basis of this in vitro model, at least two teeth on each side should be splinted when extracoronal distal extension attachment prostheses are used.

Load distribution in osseointegrated implant supporting extended and non extended dentures.

There is a controversy among prosthodontists concerning the most favourable superstructure design of a prosthesis supported by implants. Some investigators used the fully extended denture, others used a non extended. This study evaluated the load distribution pattern occurring in implants with the two designs. A real clinical situation which includes 4 osseointegrated implants that are connected to each other with a superstructure bar and support an acrylic dentures was transferred into a 3-D geometric model. With the 3-D FEM it was possible to compare between the two types of acrylic dentures.

Stress analysis of different osseointegrated implants supporting a distal extension prosthesis.

Controversy exists when implants are used to restore distal extension in edentulous patients. Some have advocated the use of a rigidly connected implant to the natural abutment teeth and others have recommended the inclusion of a stress-breaking element. In this study, a comparison between these two approaches was done. With the technology of strain gauges, it was possible to record stresses under a rigid and a resilient implant system connected to a natural abutment with the same prosthesis under the same loading conditions. The results of this study showed that a resilient implant system was better for the abutment and the implant. This study provides a test method that will help dentists in choosing implants for their patients with predictable results.

The use of precision attachments in a lower full arch rehabilitation with osseointegrated implants--a clinical report.

A technique for restoration of a case of Kennedy Class V edentulous span was described. This situation is a long edentulous span bounded anteriorly by a weak support and considered as one of the most difficult situations to restore. Two osseointegrated screw implants were inserted in the edentulous span. Together with remaining natural teeth supported a full arch restorations. Three precision attachments were included in the restoration to allow movement of the remaining teeth and to allow broken stresses at where the prosthesis extended along the corners of the mouth.

Effect of addition antimicrobial agents to denture reliners.

This study aimed at evaluating the incorporation of two antimicrobial drugs (nystatin and polynoxylin) as regards: the effect of the liner on the activity of the drug, determination of the least effective concentration of each drug and its duration of action, as well as assessment of the effect of the drug on the mechanical properties and the chemical composition of the liner. Results showed that nystatin added to denture liners in three different concentrations by weight (3%, 5%, 10%) acted effectively against Candida albicans, and that there was a direct relationship between concentration of Nystatin and its duration of action. The inhibitory effect of nystatin (10%) lasted for at least 32 weeks (end of study period). Furthermore, this concentration did not affect the strength properties of the liner. On the other hand, polynoxylin inhibited a number of strains of bacteria and Candida only in high concentrations (40-60%), and these concentrations adversely affected the strength properties of the liner.

Modification of osseointegrated implants for distal-extension prostheses.

The use of a distal implant abutment splinted to a natural tooth by a fixed partial denture has been employed for distal-extension prostheses. There is a differential difference between the viscoelastic deflection of a natural tooth by its periodontal ligament, and the almost negligible elastic deformation of an osseointegrated implant. This difference may induce a fulcrum-like effect and overstress the implant. In this study a new modification of osseointegrated implants was proposed to counteract this problem. This modification was achieved by using a resilient layer material under the superstructure of the implant. Finite element modeling (FEM) was used to examine stresses and displacement distribution around a commercially available implant and one experimental implant with a resilient layer material. The results of this study showed that the new modification is a simple and efficient way to mimic the structural natural tooth unit. It also showed that it allowed movement of the superstructure without movement of the implant three times that of the nonresilient model.

Residual ridge changes under titanium plasma-sprayed screw implant systems.

An important aspect of prosthodontic considerations of an implant is the amount of bone loss around that implant because it indicates the potential longevity and success of the whole implant system. In this study a modification of the original prosthetic design was achieved by adding a precision attachment between the complete denture and the implant screws to evaluate the effect of incorporating a stress-breaker effect on residual ridge reduction. In addition, a comparison of the rate of bone loss between the original prosthetic design and the modified precision attachment design was achieved through a longitudinal clinical study. Residual ridge changes were measured from radiographs made by a standardized serial periapical technique for a 3-year follow-up period in 10 patients divided into two groups. The results of this study showed a minimal rate of ridge reduction around the implant screws in both groups after the 3-year period. No statistical difference was found between the two groups. The results of this study presented the titanium plasma-sprayed screw implant system as an excellent clinical modality in the treatment of problematic edentulous mandibles.